Luke 1:31-35 shows Jesus as both David’s son (human lineage) and Lord (Son of God), solving the riddle posed here.

In Luke 2:11, the angel announces Jesus as Lord and Messiah — the very identity David acknowledged. This answers how David's Lord is also his son.

Romans 9:5 explicitly calls Christ 'God over all' — the divine identity implied when David calls him Lord.

Galatians 4:4 shows Jesus as God's Son born of a woman — the human birth that makes him David's son, yet he is Lord.

Revelation 22:16 declares Jesus as both Root and Offspring of David — the very paradox of David's Lord being also his son.