Was there a blood line from king david and abner?

No, Abner was not in the line of King David. Abner was the cousin of King Saul, the first King of Israel appointed by God. After the death of Saul, Abner became the commander-in-chief of the Israelite army and supported Ish-Bosheth as the son of Saul for the kingship.

On the other hand, King David was from the tribe of Judah and was anointed by God to succeed Saul. He established the Davidic dynasty, which ruled Israel for several generations. The line of King David is significant because it is believed that the Messiah, or Christ, would come from this lineage, as prophesied in the Bible.