The Lord is our witness.

Now Jephthah the Gileadite was a mighty man of valor, but he was the son of a harlot; and Gilead begot Jephthah. Gilead’s wife bore sons; and when his wife’s sons grew up, they drove Jephthah out, and said to him, “You shall have no inheritance in our father’s house, for you are the son of another woman.” Then Jephthah fled from his brothers and dwelt in the land of Tob; and worthless men banded together with Jephthah and went out raiding with him. It came to pass after a time that the people of Ammon made war against Israel. And so it was, when the people of Ammon made war against Israel, that the elders of Gilead went to get Jephthah from the land of Tob. Then they said to Jephthah, “Come and be our commander, that we may fight against the people of Ammon.” So Jephthah said to the elders of Gilead, “Did you not hate me, and expel me from my father’s house? Why have you come to me now when you are in distress?” And the elders of Gilead said to Jephthah, “That is why we have turned again to you now, that you may go with us and fight against the people of Ammon, and be our head over all the inhabitants of Gilead.” So Jephthah said to the elders of Gilead, “If you take me back home to fight against the people of Ammon, and the Lord delivers them to me, shall I be your head?” And the elders of Gilead said to Jephthah, “The Lord will be a witness between us, if we do not do according to your words.” Then Jephthah went with the elders of Gilead, and the people made him head and commander over them; and Jephthah spoke all his words before the Lord in Mizpah.
Judges 11:1-11 - NKJV