A delegation of Jewish scholars visited Imam al-Sadiq to debate with him on Islam. When they had the honor of standing before him, they asked him about the evidence and proof of the prophecy of Allah’s Apostle, may Allah bless him and his family:
-Which miracle is a proof of the prophethood of Muhammed, may Allah bless him and his family?
His (Allah’s) dominating Book that dazzles the intellects of beholders along with the lawful and the unlawful He has given, and other than them; if we mentioned it, it would take us along time to explain it.
-How can we come to know that this (miracle) is just as you have mentioned?
Imam Musa, though young, asked them:
-How can we come to know the verses Allah (revealed) to Musa (Moses) according to what you describe?
-We have known that through the narration reported by the truthful.
-Therefore, know the truthfulness of what I have told you through the answer of the boy (Imam Musa) Allah has taught without teaching and knowledge from narrators.
Imam Musa dazzled the Jews, and they believed in his words, which were really a miracle, and became Muslims, saying: “We bear witness that there is no god but Allah, that Muhammed is the Apostle of Allah, that you are the guiding Imams and the proofs of Allah over his creatures.”
Then Imam Musa mentioned this proof and the people became Muslims at his hand, Abu ‘Abd Allah (al-Sadiq) arose and kissed him on the forehead and said to him: “You are the one who will undertake the office of the Imamate (qa’im), after me.” Then he (al-Sadiq) ordered clothes and gifts to be given to them. They thanked him for that and went away.” ( Bihar al-Anwar, vol. 4, p. 148.)