41 Now while the Pharisees were gathered together, Jesus asked them a question, 42 saying, “What do you think about the Christ? Whose son is he?” They said to him, “The son of David.” 43 He said to them, “How is it then that David, in the Spirit, calls him Lord, saying,
44 “‘The Lord said to my Lord,
“Sit at my right hand,
until I put your enemies under your feet”’?45 If then David calls him Lord, how is he his son?” 46 And no one was able to answer him a word, nor from that day did anyone dare to ask him any more questions.
Matthew 22:41-46
See the article on Psalm 110:1.