Augustine of Hippo

"For a thousand years in Your sight are but as yesterday, which is past by" [Psalm 90:4]: hence we ought to turn to Your refuge, where You are without any change, from the fleeting scenes around us; since however long a time may be wished for for this life, "a thousand years in Your sight are but as yesterday:" not as tomorrow, which is to come: for all limited periods of time are reckoned as having already passed. …

Exposition on Psalm 90 ↗

Jerome

And as a watch in the night. The night has four watches, marked off in periods of three hours each, as it is said in the Gospel, "In the fourth watch of the night" Jesus "came to them," which is understood to be about cockcrow. This, then, is what he says: a thousand years with you are to be compared not only to the shortness of a day, but to the span of three hours.

Homily 67, on Psalm 89 (Alternate Series) ↗

Victorinus of Pettau

Wherefore to those seven days the Lord attributed to each a thousand years; for thus went the warning: "In Thine eyes, O Lord, a thousand years are as one day." Therefore in the eyes of the Lord each thousand of years is ordained, for I find that the Lord's eyes are seven. Wherefore, as I have narrated, that true Sabbath will be in the seventh millenary of years, when Christ with His elect shall reign.

On the Creation of the World ↗