He asked for no food. When the month was complete he took the bark of a tree, chewed it to sweeten his breath, and Allah commanded him to fast another ten nights, so that the total became forty. Hence the authentic ḥadīth states: “The odor that issues from the mouth of a fasting person is more pleasing to Allah than the scent of musk.”
When Moses resolved to depart he appointed over the community of the Children of Israel his brother Aaron—beloved, honored, and noble, his full brother on both his mother’s and father’s side and his minister in calling people to Allah—as his deputy. He instructed him and laid upon him his charge, and this in no way detracts from Moses’ exalted rank in prophethood.
Allah, Exalted is He, says: “And when Moses came at Our appointed time…”—that is, at the exact moment he had been ordered to come—“and his Lord spoke to him,” meaning that Allah spoke to him from behind a veil yet made him hear His words, calling him, confiding in him, drawing him near and bringing him close. This is a lofty station, an impregnable stronghold, a noble rank, an elevated position. May Allah’s blessings be ever renewed upon him, and His peace be upon him in this world and the next.
Granted this lofty status and elevated rank, and having heard the divine address, he sought the lifting of the veil. He said to the Magnificent One whom eyes cannot encompass, the One of overwhelming proof: “My Lord, show me, that I may look at You.” He replied, “You will never see Me.” The Almighty then clarified that Moses could not withstand His self-disclosure, for even the mountain—greater and stronger in substance and more firmly rooted than any human being—cannot remain when the Most Merciful manifests Himself.
Thus He said: “But look at the mountain; if it remains firm in its place, then you will see Me.”
The earlier scriptures relate that Allah said to him: “O Moses, no living thing can see Me without dying, and no dry (lifeless) thing without crumbling.”
In the two Ṣaḥīḥ collections it is reported from Abū Mūsā, from the Messenger of Allah (peace and blessings be upon him): “His veil is light.” In another wording: “Fire; if He were to lift it, the splendor of His Face would burn everything His sight reaches of His creation.”
Ibn ʿAbbās, commenting on the verse “Vision perceives Him not” (al-Anʿām 6:103), said: “That is His light—His very light; when He manifests Himself to something, nothing can stand before it.” For this reason the Most High said: “When his Lord manifested Himself to the mountain, He leveled it, and Moses fell unconscious; and when he revived, he said, ‘Glory be to You! I repent to You, and I am the first of the believers.’”