Ps 110:1, Mt 1:1, 2 Sam 7:12, Isa 11:1-2,10, Jer 23:5
Jesus explains to the Pharisees that Christ will come as David's descendant as Lord of David. (Mt 22:41-46)
Mt 22:41 While the Pharisees were gathered together, Jesus asked them, 42 Saying, What think ye of Christ? whose son is he? They say unto him, The son of David. 43 He saith unto them, How then doth David in spirit call him Lord, saying, 44 The Lord said unto my Lord, Sit thou on my right hand, till I make thine enemies thy footstool? 45 If David then call him Lord, how is he his son? 46 And no man was able to answer him a word, neither durst any man from that day forth ask him any more questions.
The Old Testament says that Christ is the Lord of David. (Ps 110:1)
Ps 110:1 The Lord said unto my Lord, Sit thou at my right hand, until I make thine enemies thy footstool.
Also, the Old Testament said that Christ would come as a descendant of David. (2 Sam 7:12, Isa 11:1-2, Jer 23:5)
2 Sam 7:12 And when thy days be fulfilled, and thou shalt sleep with thy fathers, I will set up thy seed after thee, which shall proceed out of thy bowels, and I will establish his kingdom.
Isa 11:1 And there shall come forth a rod out of the stem of Jesse, and a Branch shall grow out of his roots: 2 And the spirit of the Lord shall rest upon him, the spirit of wisdom and understanding, the spirit of counsel and might, the spirit of knowledge and of the fear of the Lord;
Jer 23:5 Behold, the days come, saith the Lord, that I will raise unto David a righteous Branch, and a King shall reign and prosper, and shall execute judgment and justice in the earth.
Jesus is the Lord of David, the Christ who came as a descendant of David. (Mt 1:1)
Mt 1:1 The book of the generation of Jesus Christ, the son of David, the son of Abraham.