Read 2 Samuel 17:25 Using Other Translations
And Absalom made Amasa captain of the host instead of Joab: which Amasa was a man's son, whose name was Ithra an Israelite, that went in to Abigail the daughter of Nahash, sister to Zeruiah Joab's mother.
Now Absalom had set Amasa over the army instead of Joab. Amasa was the son of a man named Ithra the Ishmaelite, who had married Abigal the daughter of Nahash, sister of Zeruiah, Joab's mother.
Absalom had appointed Amasa as commander of his army, replacing Joab, who had been commander under David. (Amasa was Joab’s cousin. His father was Jether, an Ishmaelite. His mother, Abigail daughter of Nahash, was the sister of Joab’s mother, Zeruiah.)