Jether

Avshalom had put 'Amasa in charge of the army in place of Yo'av. 'Amasa was the son of a man whose name was Yitra the Isra'eli, who had had sexual relations with Avigal the daughter of Nachash, Tz'ruyah's sister and Yo'av's mother.

"Moreover, you are aware of what Yo'av the son of Tz'ruyah did to me, that is, what he did to the two commanders of the armies of Isra'el, Avner the son of Ner and 'Amasa the son of Yeter - he killed them, shedding the blood of war in peacetime, putting the blood of war on the belt around his waist and the shoes on his feet.

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.

Avigayil was the mother of 'Amasa; the father of 'Amasa was Yeter the Yishma'eli.