2 Samuel 3:30

So Joab and Abishai his brother slew Abner, because he had slain their brother Asahel at Gibeon in the battle.

2 Samuel 2:19-23

And Asahel pursued after Abner; and in going he turned not to the right hand nor to the left from following Abner.

Proverbs 28:17

A man that doeth violence to the blood of any person shall flee to the pit; let no man stay him.

Acts 28:4

And when the barbarians saw the animal hang on his hand, they said among themselves, No doubt this man is a murderer, whom, though he hath escaped the sea, yet vengeance suffereth not to live.

Treasury of Scripture Knowledge

Summary

So Joab and Abishai his brother slew Abner, because he had slain their brother Asahel at Gibeon in the battle.

Because

Bible References

Slew abner

Proverbs 28:17
A man that doeth violence to the blood of any person shall flee to the pit; let no man stay him.
Acts 28:4
And when the barbarians saw the animal hang on his hand, they said among themselves, No doubt this man is a murderer, whom, though he hath escaped the sea, yet vengeance suffereth not to live.

Because

2 Samuel 2:19
And Asahel pursued after Abner; and in going he turned not to the right hand nor to the left from following Abner.