In another narration, Shaykh Hamza provides more details of this monumental meeting and what happened there,
"…in 1980, at a bookstore in Abu Dhabi, where I met Shaykh Abdullah Ould Siddiq of the renowned Tajakanat clan. I knew immediately he was from West Africa, given the dir'ah, the distinct West African wide robe he was wearing, as well as the turban, a rare sight in the Gulf at that time.
I had met scholars from West Africa when I was in Mali[XIX] two years before and was interested in studying with them, so I asked the Shaykh if he knew anyone who taught the classical Maliki texts in the traditional manner. He affirmed that he himself was a teacher of that very tradition…
I started to study with Shaykh Abdullah Ould Siddiq in addition to my required classes at the Islamic Institute in Al-Ain.
Unlike most Mauritanian teachers, he did not emphasize rote memorization or use of the wood slate known as the lawh. I studied directly from books. After a few years and much benefit from him and two other great Maliki jurists, Shaykh (Mohammad Ahmad Al ) Shaybani [XX]and Shaykh Bayyah Ould Salik[XXI].
My education took a major turn when I met a young electrician from the Massuma clan named Yahya Ould Khati.
He was of the view that while these scholars were excellent, the truly illustrious man of his age was Murabit al-Hajj, who lived in a forgotten part of Mauritania, far away from civilization and the distractions of this world.
He informed me that Shaykh Abdar Rahman, the son of Murabit al-Hajj, was now in the Emirates."
While Shaykh Hamza continued to study with Shaykh Abdullah Ould Siddiq, he also had to take care of his personal effects. Feeling distracted at the dormitory he moved out, into alternative housing.
"…(I became a muezzin) at a Mosque, in Al-Ain, because I didn't want to live anymore in the institute dormitory. They (The other students) were very young; I don't think a lot of them were as serious as I was.
They were just young high school students, and I was a little older and probably more serious about what I was doing. Not all of them, certainly there were some good people.
But I didn't like the environment, so I asked somebody who was at the Ministry of Religious Endowments, if they could work out a situation where I could be a Muezzin, and just live in the Mosque. Because the mosques have, in those countries, living quarters for the Muezzin and for the Imam.
I didn't take money for what I was doing, I had a stipend from the Institute, not very much, but enough to get by. So they let me do that, I was a muezzin, and I lived in the mosque."
"Shortly after, at the house of Shaykh Bayyah, an elder of the Massuma clan who had taken me under his wing and from whom I benefited greatly in my studies, I met Shaykh Abdar Rahman.
Upon meeting him, I was struck by the otherworldliness of his presence, which is not unusual for Mauritanian scholars, but it was clearly pronounced in him. I remember thinking, 'If this is the son, I must meet the father.'
I also began studying with his close friend and companion, Shaykh Hamid, after I helped him get settled and with the help of Shaykh Bashir Shaqfah, another of my teachers and at that time the head of the Office of Endowments at Al-Ain, secure a position of Imam for him in the main mosque of Al-Ain, where I was serving as a muezzin.
From Shaykh Hamid, I learned about the merits of memorization. Although I had studied several texts, and my Arabic was quite fluent by this time, Shaykh Hamid was adamant that without rote memorization, one was dependent upon books and did not really possess knowledge within oneself. Mauritanians, he told me, distinguish between daylight scholars and nighttime scholars. A daytime scholar needs light to read books to access knowledge, but a nighttime scholar can access that knowledge when the lights are out, through the strength of his memory and the retention of knowledge.[XXII] Hence, he felt that I should start over.
I had studied Ibn Ashir, al-Risalah, and sections of Aqrab al-Masalik privately; I had studied the early editions of al-Fiqh al-Maliki fi Thawbihi al-Jadid, which were used at the Institute; and I had studied Hadith with Shaykh Ahmad Badawi, one of the great Hadith scholars of Sudan. But I had put little to memory other than what I naturally retained.
Shaykh Hamid procured a slate for me and began teaching me the basics again, but with rote memorization. It was humbling, but edifying, to see how this tradition has been carried on throughout the ages with these time-tested models."
"…After a year of doing that…I learned the last portions of the Qur'an; I could recite them well. So they let me become the Imam in another mosque that was near there. And people were very generous to me, they would bring me food, and things like that."
"I was leading prayer for a community of mostly Afghan workers, who were sending their earnings back home to support families and the war effort against the Russians, who had invaded Afghanistan four years earlier.
It was then that I began to have dreams in which I saw a great man, whom I learned later, was Murabit al-Hajj. One of those dreams included an elderly woman whom I had also never seen before."
At a Diplomatic program in 2018, Shaykh Hamza spoke about his relationship with Shaykh Zayed, the Amir of Abu Dhabi:
Imam Yusuf spoke of his relationship with Sheikh Zayed. He grew up in California but called UAE “a second home” and explained how he was given a scholarship to learn Arabic and Islam. He recalled Sheikh Zayed dispatching him to Africa on philanthropic missions to help with issues such as drought, health and education. (“Interfaith Iftar at UAE Embassy in Washington Celebrates Diversity and Tolerance.” The National, 24 May 2018. https://www.thenational.ae/uae/interfaith-iftar-at-uae-embassy-in-washington-celebrates-diversity-and-tolerance-1.733436)
"I decided to leave my very comfortable and enjoyable life in the Emirates in 1984, and headed towards Mauritania via Algeria, where I planned on spending some months memorizing the Qur'an. I made this decision even though I was warned that there was a drought in Mauritania and living conditions were extremely harsh. Somehow, I felt compelled to go and nothing could deter me."
Shaykh Hamza spent several months in Algeria, and then moved on to Mauritania sooner than he expected. His exit from Algeria was due to Algerian intelligence; they arrested him as a spy.
"They didn't know what to make of this American who wanted to learn Arabic and study Islam,"
They expelled him from the country, and it was just as well, because he was to meet his destiny in Mauritania.
Shaykh Hamza had visited North Africa in 1978 soon after conversion. His second trip in 1984 would last 3 years. The country was still pre-modern (pre-modern in 1984, not so much now), still having a sizable Bedouin population and limited access to technology.
“The second time that I went, (1984) Mauritania was an isolated place. (A) lot of people (there) didn't know about America; Just that there was a country called America. I actually met people in the Saharan dessert that did not know America as a place.
It was very amazing to see people that weren't just pre-modern, but they were pre-modern people that had no interaction with the modern world“.
Regarding the educational system,
"When I got to the Sahara, I was just so overwhelmed by a people that basically had no Ministry of Education so to speak. They had no school system, they had no salaried teachers, and they had no budgets for books, nothing. Yet these extraordinary schools exist out there."
“After spending some months with Sidi Bou Said at his madrassa (Bilal ibn Rabah Madrassa ) in Tizi, Algeria, I traveled on to Tunisia, obtained a visa to Mauritania, and took a flight to Nouakchott, which lies on the Atlantic coast of the Sahara."
“I arrived in that capital city, with its extremely primitive conditions and vast slums that surrounded a small city center, with no addresses and no specific plan, other than to find Murabit al-Hajj.
I went to the marketplace and asked around if there was anyone from the Massuma clan, and was directed to a small shop where I met Abdi Salim, a very friendly man who was from the same branch of Massuma as my teacher, Shaykh Hamid. When I told Abdi Salim I wanted to find Murabit al-Hajj and study with him, his face lit up and he wholeheartedly endorsed the idea. He then took me to someone from Mukhtar al-Habib, the branch of the Massuma clan that Murabit al-Hajj was from, and they took me to the house of Mawlay al-Maqari al-Massumi, a small place made from tea boxes with open sewage in the back. Similar houses were all around, as far as the eye could see. Mawlay al-Maqari al-Massumi was one of the most hospitable and welcoming people I had ever met; I later learned he was loved by all who knew him. I stayed with him and his family for several days.
Providentially, Shaykh Abdar Rahman soon arrived from the Emirates to visit his mother and father and, not surprisingly, it was his wont to stay with Mawlay al-Maqari whenever in the capital. He would accompany me to his family's school in Tuwamirat, but the journey required camels. A message was sent to the encampment of Murabit al-Hajj via the government radio announcements, which was how people in the capital communicated with the nomads in the desert. The message stated that Shaykh Abdar Rahman and Hamza Abdul Wahid (my given name when I converted and used at that time) would be arriving in the town of Kamur on such-and-such a date and were in need of camels there to take them to their village, Tuwamirat. We then set out on a rather unpleasant journey in a truck to Kamur, which was several hundred kilometers inland into the Sahara desert. The road at that time ended at Bou Talamit, and two-thirds of it was simply rough desert track worn down over time by loaded trucks and jeeps. It was the bumpiest, dirtiest, and most difficult road journey I had ever taken in my life.
After two grueling days, we arrived in a beautiful town known as Geru, which at the time had no technology, and the buildings there were all a lovely adobe. Hundreds of students studied at seven madrassas, called Mahdharain Geru. At night, with the exception of a few flashlights, candles, and kerosene lamps, all was dark so the Sahara night sky could be seen in all its stellar glory. The entire town was filled with the soothing sounds of the recitation of Qur'an and other texts.
We stayed with Shaykh Khatri, the brother of Murabit al-Hajj's wife Maryam, and a cousin of Murabit al-Hajj. While in Geru, I came to know a great saint and scholar, Sidi Minnu, who was already an old man at the time. He memorized all of the Hisn al-Hasin of Imam al-Jazari and recited it every day. His other time was spent in praying for the entire Ummah. Once, we were sitting on the sand and he picked some up with his hand and said to me, "Never be far away from the earth, for this is our mother."
He then said something that struck me to the core: "I have never regretted anything in my entire life, nor have I ever wished for anything that I did not or could not have, but right now I wish that I was a young man so that I could accompany you on this great journey of yours to seek knowledge for the sake of God."
After a few days, we set out for Kamur, which we had passed on our way to Geru, and then took camels and set out for Murabit al-Hajj; by nightfall we arrived in Galaga, a valley with a large lake that rises and lowers with the rainfall and the seasons. After breakfast the next morning, we set out for the upper region some miles from where Murabit al-Hajj's clan was encamped.
As we came into Tuwamirat, I was completely overwhelmed by its ethereal quality. It was the quintessential place that time forgot. The entire scene reminded me of something out of the Old Testament. Many of the people had never seen a white person before and the younger people had only heard about the French occupation, but never seen French people or other foreigners for that matter. I entered the tent of Murabit al-Hajj.
My eyes fell upon the most noble and majestic person I have ever seen in my life. He called me over, put his hand on my shoulder, welcomed me warmly, and then asked me, "Is it like the dream?" I burst into a flood of tears. I had indeed experienced a dream with him that was very similar to our actual meeting.
…Murabit al-Hajj insisted that I stay with him in his tent and sleep next to him. I soon came to know his extraordinary wife, Maryam Bint Bwayba. Completely attentive to my needs, she took care to see that I was comfortable, and provided me with a running commentary on the place and its people. Maryam was one of the most selfless people I have ever met. 
It was 1985 and over the next 3 years he sat at Masjid al-Hajj, the school of Murabit al-Hajj and studied not only the sacred sciences, but also the traditional Bedouin way of life. It was a profound experience, and changed him fundamentally.
Shaykh Hamza gives an amazing account of his Master,
"Murabit al-Hajj's birth name is Sidi Muhammad ould Fahfu al-Massumi, and he was nicknamed Hajj Umar by his mother after the great scholar and warrior, "Umar Tal of Senegal".
During the blessed time that I was fortunate to have lived with him in his own tent, I observed his daily routine: He would usually awake at about 2:30 or 3:00 in the morning and begin the Tahajjud or night prayers. He would often recite for a few hours, and I heard him repeat verses over and over again and weep. Just before dawn, he would sit outside his tent and recite Qur'an, and then when the first light of dawn was discernible, he would walk to the open-air mosque and call the adhan. He would then pray his nafilah and wait for a short period and then call the iqamah. During that time, I never saw anyone else lead the prayer, and he would almost always recite from the last 60th of the Qur'an as is the Sunnah for a congressional Imam to do so according to Imam Malik.
After the sun rose and reached the level of a spear above the horizon, he would pray the sunrise rak'ahs and then return to his tent where he would have some milk brought fresh from a cow. He would then teach until about 11:00 in the morning and nap for a short while. After that, students would start coming again, and he would continue to teach until about 1:00pm at which time he would measure his shadow for the time of the midday prayer. He would then call the adhan at the time his shadow reached an arm's length past the post meridian time as is the Maliki position on the midday prayer, if performed in congregation, to allow for others to come from their work after the heat dissipates. He would always pray four rak’ahs before and after the midday prayer and then return to his tent where he would teach until afternoon. He would usually have a small amount of rice and yogurt drink that is common in West Africa. Then, he would measure his shadow for the afternoon prayer, and when he ascertained its time, he would proceed to the mosque and call the adhan.
After Asr, Murabit al-Hajj would return to his tent and usually resume teaching and sometimes listen to students recite their Qur'an lessons from memory and he would correct their mistakes. During any lulls in his teaching, anyone in his presence could hear him say with almost every breath, "La ilaha illa Allah," or he would recite Qur'an. At sunset, he would go and call the adhan, pray Maghrib, and then sit in the mihrab and recite his wird until the time of the night prayer. He would call the adhan, lead the pray and return to his tent. He would usually have some milk and a little couscous and then listen to students recite Qur'an or read Qur'an by himself. At around 9:00 pm he would admonish himself with lines of poetry from Imam Shafi's Diwan and other well-known poets. He would often remember death with certain lines that he repeated over and over again, especially the following that I heard from him many times:
O my Lord, when that which there is repelling alights upon me,
And I find myself leaving this adobe
And become Your guest in a dark and lonely place,
Then make the host's meal for his guest the removal of my wrongs.
A guest is always honored at the hands of a generous host,
And You are the Generous, the Creator, the Originator.
Surely kings, as a way of displaying their magnanimity
Free their servants who have grown old in their service.
And I have grown old in Your service,
So free my soul from the Fire
He often repeats these lines for what seems like an eternity, his voice penetrating the hearts of all those within earshot. He once admonished me with lines of poetry, one after another, until I wanted the earth to swallow me. He said to me, "And what is man other than a comet that flashes brilliant light for a moment only to be reduced to ashes."
He told me several times, "Hamza, this world is an ocean, and those who drown in it are untold numbers. Don't drown."
I have never seen anyone like him before him or after him, and I don't think that I ever will. May Allah reward him for his service to this deen and his love and concern for the Muslims. He was never known to speak ill of anyone. Once when a student was studying Khalil with him and asked what a certain word meant in the text, he explained to him that it was a slow and clumsy horse. The student then said, "like so-and-so's horse?" At this Murabit al-Hajj suddenly became upset and said, "I don't spend much time with people because they backbite, so if you want to study with me, you must never speak ill of anyone in my presence." It is not well known by Muslims that to speak ill of someone's animals falls under the ruling of backbiting.
Shaykh Murabit al-Hajj is a master of the sciences of Islam, but perhaps more wondrous than that, he has mastered his own soul. His discipline is almost angelic, and his presence is so majestic and ethereal that the one in it experiences a palpable stillness in the soul. As the Arabs say, "the one who hears is not as the one who has seen." I was told by many people from his family that had I seen him in his youth, I would have been even more astonished at his devotional practices.
He is recognized in Mauritania as being one of the last great scholars, and his fatwa is highly respected among the people of West Africa who know of him, and they are many."
In another article, Shaykh Hamza commented on his "transparency":
"I never heard him say anything unkind or unflattering about anyone. A cousin of his who has known him for seventy years affirmed this as well.
Murabit al-Hajj never complained or criticized the weather, the food, the company, or any of the hardships so evident in the lives of West African nomads.
Once, a man from Geru, a nearby village, saw Murabit al-Hajj in a dream in which he was praying naked.
Embarrassed, this man went to a well-known dream interpreter and told him the dream but not the identity of the naked man.
The interpreter said, "That could only have been Murabit al-Hajj, because I don't know anyone who prays in a completely pure-hearted state other than him."