The book of the genealogy of Jesus Christ, the son of David, the son of Abraham.
All Commentaries on Matthew 1:1 Go To Matthew 1
Matthew wrote for the Jews, and in Hebrew ; to them it was unnecessary to explain the divinity which they recognized; but necessary to unfold the mystery of the Incarnation. John wrote in Greek for the Gentiles who knew nothing of a Son of God. They required therefore to be told first, that the Son of God was God, then that this Deity was incarnate.
And do not consider this genealogy a small thing to hear: for truly it is a marvellous thing that God should descend to be born of a woman, and to have as His ancestors David and Abraham.
But why would it not have been enough to name one of them, David alone, or Abraham alone? Because the promise had been made to both of Christ to be born of their seed. To Abraham, “And in thy seed shall all the nations of the earth be blessed.” David was king and prophet, but not priest. Thus He is expressly called the son of both, that the threefold dignity of His forefathers might be recognized by hereditary right in Christ.
Another reason is that royal dignity is above natural, though Abraham was first in time, yet David is honour.