Mark 12:36

For David himself said by the Holy Ghost
In ( Psalms 110:1 ) , being inspired by the Spirit of God:

the Lord said to my Lord, sit thou on my right hand, till I make
thine enemies thy footstool.
This is a proof, that David did call Christ his Lord; and that he called him so in spirit; since these words were delivered by him under the inspiration of the Holy Spirit: that the psalm was wrote by David, the title shows; and that he spake it as he was influenced by the Holy Ghost, our Lord declares: the passage relates to what God the Father said to Christ, when being risen from the dead, he ascended on high, and entered into the most holy place; he bid him sit down at his right hand, as having done the work of man's salvation, he was sent about, to full satisfaction; and as a mark of affection to him, and honour conferred upon him in the human nature; where he should continue, till all his enemies, Jews, Pagans, Papists, and Mahometans, as well as Satan, and all his principalities and powers, were so subdued under him, as to be as a footstool to his throne: and when David prophetically speaks of this, he calls the Messiah his Lord; saying, the "Lord said to my Lord"; on which account the prophecy is cited; who was so, as he is God, and his Creator and Redeemer. That this prophecy is a prophecy of the Messiah, and is applicable to no other but he; and is therefore pertinently cited, and applied to him here, (See Gill on Matthew 22:44).