M'lakhim Alef (1 Ki) 2:32

ADONAI will bring his blood back on his own head, because he struck down two men more righteous and better than he — he killed them with the sword without my father David’s awareness: Avner the son of Ner, commander of the army of Isra’el, and ‘Amasa the son of Yeter, commander of the army of Y’hudah.