Lit. “The Ascents.” The title of the LXXth chapter of the Qur’an, in the second verse of which occurs the sentence: “God, the possessor of the Ascents (or Steps) by which the angels ascend unto Him, and the Spirit (i.e. Gabriel), in a day whose space is fifty thousand years.”
Sale, translating from al-Baizawi and Zamakhsahri says: “This is supposed to be the space which would be required for their ascent from the lowest part of the creation to the throne of God, if it were to be measured, or the time which it would take a man to perform a journey; and this is not contradictory to what is said elsewhere (if it be to be interpreted to the ascent of the angels), that the length of the day whereon they ascend is 1,000 years, because that is meant only of their ascent from earth to the lower Heaven, including also the time of their descent.
“But the commentators, generally taking the day spoken of in both these passages to be the Day of Judgment, have recourse to several expedients to reconcile them, and as both passages seem to contradict what Muhamman doctors teach, that God will judge all creatures in the space of half-a-day, they suppose those large numbers of years are designed to express the time of the previous attendance of those who are to be judged, or else to the space wherein God will judge the unbelieving nations, of which, they say, there will be fifty, the trial of each nation taking up 1,000 years, though that of the true believers will be over in the short space above mentioned.”
Based on Hughes, Dictionary of Islam