Prayer, preceded by ablutions, was the first duty taught to the Prophet by the celestial envoy. Mohammad, having returned to the place where he had first heard the Revelation, Jibra'il appeared again, in the shape of a human being. 'O Prophet!' he said, 'You must lead men to proclaim that there is no God but Allah.' He drove him towards a watercourse where Jibra'il stamped on the ground with his foot. A spring immediately gushed forth, and setting the example, the angel taught Mohammad the rites of Purification by means of ablutions preceding all prayers. He then went through the prayers, with the bowing, prostrations and sentences of which they should be comprised; and the Prophet prayed with him, guided by the angel's movements and words. Mohammad felt his body relieved from a weighty burden by the purification, and his soul brightened by the benefits of these prayers. Then it was that, thrilling with the faith of belief, Mohammad was about to return home to his wife when Jibra'il appearing once more, said to him: 'Teach Khadijah salvation by Islam!' That is to say, by voluntary resignation to all the Creator's commands. He obeyed and spoke thus: 'O Khadijah! Jibra'il ordereth me to teach thee salvation by Islam.' And Khadijah answered: 'Allah is Salvation; from Him cometh Salvation, and let Salvation be on Jibra'il.' Thus it came about that, of all living beings, Khadijah was Islam's first convert. The Prophet took her at once to the miraculous spring, where he taught her what he had just learnt. Copying her husband, she purified herself by the ablutions and recited the prayers. Ever since that day, Allah made use of this admirable woman to mitigate the sorrows and pains of His Prophet in all the ordeals he had to undergo. Khadijah's devotion endowed Mohammad with deep contempt for mortals' wickedness, and his wife's firm faith served to comfort him when he was looked upon as an impostor. One of the first of the Prophet's companions to believe in his mission was Ali, son of Abu Talib, only about ten years old just then, and who Mohammad had adopted during a period of famine, so as to relieve his uncle, at the head of a very large family. Noticing that Mohammad and Khadijah kept aloof and became absorbed in prayer, he marvelled greatly at seeing no object of worship set up in front of them and he put this question to the Prophet: 'What rites were ye both performing just now?'--'We were saying the prayers of the pure religion that Allah hath just chosen for Himself and for which He hath chosen me to be the Prophet,' he replied. 'O Ali! I do invite thee to join with me. I invite thee to worship the Only Allah that hath no partners and I call upon thee to renounce the idols Lat and Uzza who can neither benefit nor harm their worshippers.'