Judges 11:9-13

So Jephthah said to the elders of Gilead, “If you bring me back to fight against the sons of Ammon and the Lord gives them up to me, will I become your head?”

And the elders of Gilead said to Jephthah, “The Lord is witness between us; be assured we will do as you have said.”

Then Jephthah went with the elders of Gilead, and the people made him head and leader over them; and Jephthah spoke all his words before the Lord at Mizpah.

So Jephthah sent messengers to the king of the sons of Ammon, saying, “What conflict do you and I have, that you have come to me to fight against my land?”

And the king of the sons of Ammon said to the messengers of Jephthah, “It is because Israel took my land when they came up from Egypt, from the Arnon as far as the Jabbok and the Jordan; so return them peaceably now.”