Charles Ellicott Commentary Hebrews 1:13

"But of which of the angels hath he said at any time, Sit thou on my right hand, Till I make thine enemies the footstool of thy feet?" — Hebrews 1:13 (ASV)

But to which of the angels.—The final appeal is made to that Psalm which more frequently than any other is quoted in reference to Christ, and which we have already seen to be the source of all the New Testament references to the Savior’s session at the right hand of God. It is not necessary to say much here regarding Psalm 110:1, to which so many allusions will be made in the course of this Epistle.

That it was regularly understood by the Jews in our Lord’s time to be a Messianic Psalm is clear both from Matthew 22:43–44 and from the independent accounts we possess. Most probably, it stands alone among the Psalms as being simply prophetic: these words have never been addressed either to angels or to an earthly king. On the special words of the quotation, see Hebrews 1:3.

Said he at any time.—Better, has He ever said.

Until I make . . .—Literally, until I have made Your enemies a footstool of Your feet.