Neither, because they are the seed of Abraham,
are they all children: but, In Isaac shall thy seed be called. - Rom 9:7
Now see the connection - Abraham is the Father and his only begotten son, Isaac, thru Sarah.
Isaac was the Promise from God to Abraham/Sarah to reveal to us that Jesus is the Promise of the Father
Now King David was chosen by God to be King over Israel - not chosen by man.
David committed adultery and pre-meditated murder(the worse kind) - yet God had Mercy on him.
Therefore David is the Son of Abraham for the Father sent His Son so that Mercy triumphs over judgment.
And Christ is both King and Priest according to the Order of Melchizidek = just as David ate the Show-Bread that was forbidden but only for the Priests.
Now it happened that He went through the grainfields on the Sabbath; and as they went His disciples began to pluck the heads of grain.
24And the Pharisees said to Him, “Look, why do they do what is not lawful on the Sabbath?”
25But He said to them, “Have you never read what David did when he was in need and hungry, he and those with him:
26how he went into the house of God
in the days of Abiathar the high priest, and ate the showbread, which is not lawful to eat except for the priests, and also gave some to those who were with him?”
27And He said to them, “The Sabbath was made for man, and not man for the Sabbath.
28Therefore the Son of Man is also Lord of the Sabbath.”