He was now exposed to many insults and much annoyance. The insecurity in which he lived at Mecca forced him to seek supporters elsewhere. Now the Caaba or holy stone at Mecca was the scene of an annual pilgrimage from the surrounding country. Mahomet made use of the advent of the pilgrims in 621 to enlist in his cause six inhabitants of Medina, who are reported to have bound themselves to him by the following vow:—Not to consider any one equal to Allah; not to steal; not to be unchaste; not to kill their children; not willfully to calumniate; to obey the prophet's orders in equitable matters. Paradise was to be the guerdon of the strict observance of this vow, which from the place where it was taken was called the first Akaba. In the following year, 622, Mahomet met seventy-two men of Medina by night at the same ravine, and the oath now taken was the second Akaba. The believers swore to receive the prophet and to expend their property and their blood in his defense. Twelve of the seventy-two disciples were selected as elders, the prophet following therein the example of Christ. A place of refuge from the hostility of their countrymen was now open to the rising sect. All the Moslems who were able and willing gradually found their way to Medina. At length none of the intending emigrants remained at Mecca but the prophet himself and his two friends Abu Bakr, and Ali. The designs of the Korayschites against Mahomet's life failed, and he effected his escape to a cave at some little distance from Mecca, and in the opposite direction from Medina. Here he remained in concealment with Abu Bakr for three days, the daughter of the latter bringing food for both. After this time a guide brought three camels with which they proceeded in safety to Medina. The prophet reached Koba, a village just outside it, on the 14th of September 622. He remained here three days, and received the visits of his adherents in Medina every day. This was the celebrated Hegira, or flight, from which the Mussulman era is dated.