Cyril-of-JerusalemLet us not curiously pry into what is properly meant by the throne; for it is incomprehensible.

But neither let us endure those who falsely say, that it was after His Cross and Resurrection and Ascension into heaven, that the Son began to sit on the right hand of the Father.

For the Son gained not His throne by advancement; but throughout His being (and His being is by an eternal generation) He also sitteth together with the Father.

And this throne the Prophet Esaias having beheld before the incarnate coming of the Saviour, says, I saw the Lord sitting on a throne, high and lifted up  (Is. 6:1), and the rest.

For the Father no man hath seen at any time (John 1:18), and He who then appeared to the Prophet was the Son.

The Psalmist also says, Thy throne is prepared of old; Thou art from everlasting (Ps. 93:2).

[…] But now I must remind you of a few things out of many which are spoken concerning the Son’s sitting at the right hand of the Father.

For the hundred and ninth Psalm says plainly, The Lord said unto my Lord, Sit Thou on My right hand, until I make Thine enemies Thy footstool (Ps. 110:1).

And the Saviour, confirming this saying in the Gospels, says that David spoke not these things of himself, but from the inspiration of the Holy Ghost, saying, How then doth David in the Spirit call Him Lord, saying, The Lord said unto my Lord, Sit Thou on My right hand (Matt. 22:3)?

And in the Acts of the Apostles, Peter on the day of Pentecost standing with the Eleven (Acts 2:34), and discoursing to the Israelites, has in very words cited this testimony from the hundred and ninth Psalm.

[…] Now may He Himself, the God of all, who is Father of the Christ, and our Lord Jesus Christ, who came down, and ascended, and sitteth together with the Father, watch over your souls.

May He keep unshaken and unchanged your hope in Him who rose again; raise you together with Him from your dead sins unto His heavenly gift; count you worthy to be caught up in the clouds, to meet the Lord in the air (1 Thess. 4:17).

[…] Think not that because He is now absent in the flesh, He is therefore absent also in the Spirit.  He is here present in the midst of us, listening to what is said of Him, and beholding thine inward thoughts, and trying the reins and hearts (Ps. 7:9).

And He is also now ready to present those who are coming to baptism, and all of you, in the Holy Ghost to the Father, and to say,Behold, I and the children whom God hath given Me (Isa. 8:18; Heb. 2:13).

Cyril of Jerusalem (c. 313-386): Catechetical Lectures 14, 27, 28, 30.