Jephthah of Gilead is a mighty warrior, the son of a prostitute. His half brothers drive him out so he will not inherit, and he flees to the land of Tob, where worthless men gather around him. When the Ammonites attack Israel, the elders of Gilead go to fetch him and ask him to be their chief. Jephthah reminds them that they drove him out, but he accepts, on the condition that if the Lord gives them victory he will be their head. They swear it before the Lord at Mizpah.
Jephthah sends messengers to the king of Ammon, who claims the land between the Arnon and the Jabbok, saying that Israel took it. Jephthah replies with a review of history: when Israel came out of Egypt, it did not take land from Moab or Ammon; it was Sihon, king of the Amorites, who attacked, and the Lord gave Sihon to Israel. They have lived there three hundred years, and the Lord, the Judge, will decide between Israel and Ammon. The Ammonite king does not listen.
The Spirit of the Lord comes on Jephthah, who passes through Gilead and Manasseh and makes a vow: if the Lord gives the Ammonites into his hand, whatever comes out of the doors of his house to meet him will be the Lord's and he will offer it as a burnt offering. Jephthah defeats the Ammonites, takes twenty cities and subdues them. When he returns to Mizpah, his daughter comes out to meet him, dancing with tambourines. She was his only child. Jephthah tears his clothes and says he cannot take back his vow. She asks for two months to mourn her virginity on the mountains with her companions. When the time has passed, he did to her as he had vowed, and she had never known a man. From this arose the custom that each year the daughters of Israel go for four days to remember Jephthah's daughter.