It is related from Ibn Abbas that he said: The Quraysh gathered and said, “Muhammad grew up among us known for trustworthiness and truthfulness, and we never accused him of lying. Yet he has made the claims he has made. Send a group of men to the Jews in Medina and ask them about him, for they are People of the Scripture.” So they sent a group to them, and the Jews said: “Ask him about three matters. If he answers all of them, or answers none of them, then he is not a prophet. But if he answers two and does not answer one, then he is a prophet. Ask him about some youths who disappeared in ancient times: what was their story? They had a remarkable tale. Ask him also about a man who reached the east and west of the earth: what is his story? And ask him about the Spirit.”
So they questioned him, and the Prophet, may Allah bless him and grant him peace, said, “I will inform you tomorrow about what you have asked me.” But he did not say, “If Allah wills.” Revelation then ceased—for twelve nights, according to Mujahid; fifteen days, according to another report; and forty days, according to Ikrimah—while the people of Mecca said, “Muhammad promised us tomorrow, yet morning after morning has come and he has told us nothing.” The Prophet, may Allah bless him and grant him peace, was grieved by the delay in revelation and distressed by what the people of Mecca were saying. Then (1) Gabriel descended with His words: “Never say of anything, ‘I will certainly do this tomorrow,’ without adding, ‘if Allah wills.’”
Concerning the story of the youths, He revealed: “Or did you think that the people of the Cave and the Inscription were, among Our signs, something wondrous?” (2) Concerning the one who reached the east and west, He revealed: “They ask you about Dhu al-Qarnayn.” And concerning the Spirit, He revealed: “They ask you about the Spirit. Say, ‘The Spirit is of the command of my Lord.’” (3)
They differed over the Spirit about which the question was asked. It is related from Ibn Abbas that it was Gabriel; this was also the view of al-Hasan and Qatadah.
It is related from Ali that he said: “It is an angel with seventy thousand faces, each face having seventy thousand tongues, with all of which he glorifies Allah, exalted is He.”
Mujahid said: “They are a created being in the form of the children of Adam, with hands, feet, and heads. They are neither angels nor human beings, yet they eat food.”
Said ibn Jubayr said: “Apart from the Throne, Allah, exalted is He, has not created anything greater than the Spirit. If it wished to swallow the seven heavens, the seven earths, and all that is in them in a single mouthful, it could do so. Its bodily form resembles that of the angels, while its face resembles that of human beings. On the Day of Resurrection, it will stand to the right of the Throne. It is the closest of all created beings to Allah, exalted is He; it is now behind seventy veils, and on the Day of Resurrection it will be even closer to Allah. It is among those who will intercede for the people of tawhid. Were it not for a veil of light between it and the angels, the inhabitants of the heavens would be burned by its light.”
It was also said that the Spirit is the Quran.