NET
30 So Joab and his brother Abishai killed Abner, because he had killed their brother Asahel in Gibeon during the battle.
Darby
30 So Joab and Abishai his brother killed Abner, because he had slain their brother Asahel at Gibeon in the battle.
KJV
30 So Joab and Abishai his brother slew Abner, because he had slain their brother Asahel at Gibeon in the battle.