2 Samuel 3:27

3:27 When Abner returned to Hebron, Joab took him aside at the gate as if to speak privately with him. Joab then stabbed him in the abdomen and killed him, avenging the shed blood of his brother Asahel.

2 Samuel 20:10

20:10 Amasa did not protect himself from the knife in Joab’s other hand, and Joab stabbed him in the abdomen, causing Amasa’s intestines to spill out on the ground. There was no need to stab him again; the first blow was fatal. Then Joab and his brother Abishai pursued Sheba son of Bicri.