Bible Verses About Treachery: Of Joab

After leaving David, Yo'av sent messengers after Avner, and they brought him back from the water cistern at Sirah without David's knowledge.

Upon Avner's return to Hevron, Yo'av took him aside into the space between the outer and inner city gates as if to speak with him privately; and there he struck him in the groin, so that he died - thus avenging the death of 'Asah'el his brother.