Abigail

Now Absalom appointed Amasa in Joab's stead over the army: and Amasa was the son of a man who was called Jethra, of Jezrael, who went in to Abigail the daughter of Naas, the sister of Sarvia who was the mother of Joab.

And their sisters were Sarvia, and Abigail. The sons of Sarvia: Abisai, Joab, and Asael, three.

And Abigail bore Amasa, whose father was Jether the Ismahelite.