Irenaeus (130 - 202 AD)

Also, towards the conclusion of his Gospel, Mark says: “So then, after the Lord Jesus had spoken to them, He was received up into heaven, and sitteth on the right hand of God;” confirming what had been spoken by the prophet: “The Lord said to my Lord, Sit Thou on My right hand, until I make Thy foes Thy footstool.”

Thus God and the Father are truly one and the same; He who was announced by the prophets, and handed down by the true Gospel; whom we Christians worship and love with the whole heart, as the Maker of heaven and earth, and of all things therein.

Source: Against Heresies, Book III, Chapter 10, Paragraph 5 [read online]