Judges 11:9-11

So Jephthah said to the elders of Gilead, “If you take me back [home] to fight against the Ammonites and the LORD gives them over to me, will I [really] become your head?” The elders of Gilead said to Jephthah, “The LORD is the witness between us; be assured that we will do as you have said.” So Jephthah went with the elders of Gilead, and the people made him head and leader over them. And Jephthah repeated everything that he had promised before the LORD at Mizpah.