Repayment for shed blood of innocent men

1 King 2:28-35
The Lord will May the guilt of their blood rest on the head of Joab and his descendants forever. Repay him for the blood he shed, because without my father David knowing it he attacked two men.
May the guilt of their blood rest on the head of Joab and his descendants forever.
And Joab dies the violent death he has meted out to others.
Why?
Because without David knowing it he attacked two men and killed them with the sword. Both of them—Abner son of Ner, and Amasa son of Jether—were better men and more upright than he.
Joab killed innocent people for his own ambitions. Joan is royal to David, but did not follow the way of God.
How?
Let me be good follower before the Lord and be a good staff before men.