Origen's Commentary on the Gospel of John: Book I. 32Christ as Son.

32. Christ as Son. None of these testimonies, however, sets forth distinctly the Saviour's exalted birth; but when the words are addressed to Him, "Thou art My Son, this day have I begotten Thee," this is spoken to Him by God, with whom all time is to-day, for there is no evening with God, as I consider, and there is no morning, nothing but time that stretches out, along with His unbeginning and unseen life. The day is to-day with Him in which the Son was begotten, and thus the beginning of His birth is not found, as neither is the day of it.