2 Samuel 17:24-26

David went to Mahanaim, and Absalom crossed the Jordan with all the men of Israel. Absalom had appointed Amasa over the army in place of Joab. Amasa was the son of Jether, an Ishmaelite who had married Abigail, the daughter of Nahash and sister of Zeruiah the mother of Joab. The Israelites and Absalom camped in the land of Gilead.