MATTHEW 22 34 But when the Pharisees heard that He had silenced the Sadducees, they gathered together. 35 Then one of them, a lawyer, asked Him a question, testing Him, and saying, 36 “Teacher, which is the great commandment in the law?”37 Jesus said to him, “‘You shall love the Lord your God with all your heart, with all your soul, and with all your mind.’ 38 This is the first and great commandment. 39 And the second is like it: ‘You shall love your neighbor as yourself.’ 40 On these two commandments hang all the Law and the Prophets.”41 While the Pharisees were gathered together, Jesus asked them, 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 then does David in the Spirit call Him ‘Lord,’ saying:44 ‘The Lord said to my Lord,“Sit at My right hand,Till I make Your enemies Your footstool”’? 45 If David then calls Him ‘Lord,’ how is He his Son?” 46 And no one was able to answer Him a word, nor from that day on did anyone dare question Him anymore.

From the prophecies of David, He reveals the truth that He is – the Lord will show them His divinity. The Pharisees said that the Christ is the son of David, that is a simple man. But the Lord replies: “How then does David call him Lord” – not just calls the Lord, for “by inspiration,” that is, by the gift of grace of the Spirit, received the revelation of Him. With these words, the Lord did not deny that he – the son of David, but reveals that he is not just a man descended from the seed of David. So ask the Lord to the Pharisees or admitted they did not know, they asked him, and know or truly confess believe, or, finally, finding no answer, went with derision, and no longer dared to ask him.
(St. Theophylact)