Theophylact of Bulgaria
Because Christ was coming to His Passion, He corrects a false opinion of the Jews, who said that Christ was the Son of David, not his Lord; wherefore it is said, And Jesus answered and said, while he taught in the temple.
But Christ shews Himself to be the Lord, by the words of David. For it goes on: For David himself said by the Holy Ghost, The Lord said to my Lord, Sit thou on my right hand; as if He had said, Ye cannot say that David said this without the grace of the Holy Spirit, but he called Him Lord in the Holy Spirit; and that He is Lord, he shews, by this that is added, Till I make thine enemies thy footstool; for they themselves were His enemies, whom God put under the footstool of Christ.