Is it permissible to say that the Qur'an is ancient, and what are the evidences for that?

The description of the Qur'an as "eternal" or "ancient" carries two meanings:

The first is invalid, which is that the Qur'an is an eternal meaning spoken by God in eternity. This is an innovated saying originating from the Ash'aris' view that God's speech is a single meaning subsisting in the self, or that its letters are eternal and ancient, subsisting in the essence of the Lord. None of the predecessors (Salaf) held this view.

The second meaning is correct, which is that the Qur'an is uncreated, and that the genus of God's speech is eternal, and that He has always been a speaker whenever and however He wills. This is what the أهل السنة (Ahl al-Sunnah) intend by their statement that God's speech is eternal; meaning its genus is eternal, not that the specific speech itself is eternal and ancient with the eternity of God. So the Qur'an is the revealed, uncreated speech of God; it is eternal in its type, but individual instances of it are originated.