Abraham was Syrian by birth. He was a wealthy merchant who visited Egypt several times, and finally stayed there. He was known for his goodness, devoutness and love of the poor. After his ordinatlon, he distributed half of his wealth to the needy and used the other half for building churches throughout Egypt.
During the reign of Al-Muizz - who was the first Fatimid ruler of Egypt - the Islamic government was ambivalent in its treatment of the Copts, alternating sympathy and tolerance with atrocity and brutality. At that time, St. Mark's Seat had been vacant for about two years. Finally the bishops and Coptic community leaders assembled in the Church of St. Serguis in order to choose possible candidates. While they were convening, Abraham the Syrian, a man devoted to religion and piety, entered the church and they unanimously decided to elect him. They took him to Alexandria where he was consecrated as the 62nd Patriarch.
As for Al-Muizz, he was known for tolerance and interest in debates on religious matters. He had a Jewish minister called Ibn-Killis who informed him that it is written in the book of the Nazarines (the New Testament of course) that "If you have faith as a mustard seed, you will say to the mountain move from here to there, and it will move." (Matt. 17:20 & Mark 11:23) He showed this verse to the Caliph and persuaded him to challenge the Pope to order the Muqattam Mountain, east of Cairo, to move if he had as little faith as the small mustard seed.
The Caliph sent for the Pope and asked him if such a verse really existed. When Pope Abraham affirmed that it was true, Al-Muizz challenged him to prove it or else the Copts would be subjected to the sword. The Pope asked for a three-day respite.
He went directly to St Mary's Church (Al Muallaqa), sent for bishops and priests and exhorted them to fast and pray for the duration of those three days. Before the dawn of the third day, the Pope, exhausted by grief and the long vigil he had kept, dozed off. The Virgin Mary came to him in his sleep and inquired: "What is with you?." "My lady, you surely know what is happening," he replied. Thereupon, she comforted him and told him that if he went through the iron gate leading to the market, he would meet a one-eyed man carrying a sack of water. This is the man who would move the mountain, she said.
The Pope hurried out in the early morning to do as she said and he met Simon the Tanner. He asked Simon what he was doing at this early hour. To which Simon replied that he was carrying water to the sick and the old who could not fetch water for themselves. He said this was his practice every morning -- to carry on his back a sack of water for the needy -- before going to work at a hide tannery. When the Pope explained his purpose, Simon was reluctant at first but when he was told of the Pope's vision, he placed himself at his disposal.
The two led a large gathering of the faithful and marched to the Muqattam Mountain. Beside them were the Caliph and his minister who had already incited many people against the Copts. Abraham celebrated mass and the multitude chanted after him Kyrie Layson, pleading for God's mercy. They knelt down three times as the Pope made the sign of the cross with a sweeping gesture extending from one end of the mountain to the other.
The mountain shook violently as if a strong earthquake had hit the land. Then it began moving upwards. Every time the worshippers rose from their prayers, the mountain lifted itself upwards. When they knelt down, it also came down with a big bang. This happened three times and every time the mountain moved upwards, the rays of the sun, which was behind it, swept through the space separating the earth from the mountain and became clearly visible to the assembled crowd.
At this awesome sight, Al Muizz proclalmed, "God is Great!" Turning to Pope Abraham, he said, "This is enough to prove that your falth is true." Naturally, this miraculous event caused a tumult among the crowd. When order was re-established, Pope Abraham looked for Simon, who had kept himself hidden behind the Pope throughout the prayers, but he was nowhere to be found.
Simon was never seen again and there are two versions of what befell him. According to bequeathed tradition, he was snatched away by an angelic host so that the Lord may reward him for his humility. Another story claims that Simon, fearing the praise of men, disappeared voluntarily in order to protect himself from falling into the sin of vainglory.
The Caliph, who was still shaking with fear, embraced the Pope warmly and this marked the beginning of a long friendship between the two. The Caliph asked the Pope to name his reward. After some hesitation, the Pope asked for permission to rebuild or renovate some churches, particularly that of St. Mercurius in Babylon in what is now old Cairo. That Church, which was partly destroyed, was being used as a sugar warehouse. The Caliph offered funds from the state treasury for the reconstruction of the Church but Abraam turned him down. "He whose Church we are building does not need the money of this world and is capable of helping us until we finish the job," Abraam said.
The Pope also decreed that the three-day grace period which he had requested from the Caliph, and which he and the bishops and priests spent in prayer and fasting, be a regular period of fasting to be observed by all Copts every year. Those three days were added to the forty days of fasting before Christmas. Thus, the Advent fasting became forty-three days starting on November 25.
Shortly after the miracle took place, Al Muizz decided to convert to Christianity. A baptismal font, big enough for the immersion of a grown-up man, was built for him in St. Mercurius Church. This font continues to exist until the present day and is known as "Maamoudiat Al-Sultan" which means the baptistry of the Sultan.