Yazid Bin Sulayt was trustworthy and trusted. He was among the men of piety and knowledge. He and a group of his companions made the pilgrimage to the Sacred House of Allah (Mecca). On his way, he met Imam Abu 'Abd Allah (al-Sadiq), who was accompanied by his sons and retainers. He hurried to the Imam to ask him about the Imam after him, saying: "May my father and mother be your ransom; you are the purified Imams; none escapes from death; who is the Imam after you?" The Imam, peace be on him, indicated with his hand to his son Musa and explained his ideals with which he was endowed. He said: "He has the knowledge of wisdom, understanding, generosity, knowledge of that which men need and of the affairs of their religion over which they differ. He has good manners and good neighborhood; he is one of Allah's gates; he has another (quality) that is the best of all these (qualities)."
-May my father and mother be your ransom, what is it?
-Allah, the Most High, will bring forth from him the succor of this community, its relief, its knowledge, its light, its understanding, and its wise man, the best baby and youth. Through him Allah will prevent bloodshed, correct discords, bring together the people of separation, make peace among (them), clothe the naked, satisfy the hungry, make the fearful safe, and send rain down. Men obey him; the best middle-aged one and young man; his words are a decision; his silence is knowledge; he explained to men that over which they differ." ( Bihar al-Anwar, vol. 11, p. 234.)