2 Samuel 20:9-10

9And Joab said to Amasa, "Is it well with you, my brother?" And Joab took Amasa by the beard with his right hand to kiss him.

10But Amasa did not observe the sword that was in Joab's hand. So Joab struck him with it in the stomach and spilled his entrails to the ground without striking a second blow, and he died. Then Joab and Abishai his brother pursued Sheba the son of Bichri.