The elders of Gilead came to Jephthah in the land of Tob because the Ammonites were making war against Israel. Jephthah was the son of a harlot, and his half-brothers had driven him out of his father's house, telling him he would not inherit because he was the son of another woman. Now the same men who had hated him came asking him to be their chief and lead the fight.
Jephthah did not accept immediately. He reminded the elders that they had hated him and driven him out, and he asked why they came to him now only when they were in distress. The elders promised that if he went with them and the Lord delivered the Ammonites into his hand, he would be their head over all the inhabitants of Gilead. Jephthah made them swear before the Lord, and then he went with them. The people made him head and chief, and Jephthah spoke all his words before the Lord in Mizpah.
Before going to war, Jephthah sent messengers to the king of the Ammonites, asking what grievance he had against Israel that he was coming to fight. The king replied that Israel had taken his land when they came up from Egypt, from the Arnon to the Jabbok and to the Jordan, and he demanded its return.
Jephthah sent messengers a second time with a detailed answer. He said Israel had not taken the land of Moab or the land of the Ammonites. When Israel came from Egypt, they had asked the king of Edom for passage and been refused, and the same with the king of Moab. So Israel went around Edom and Moab and camped beyond the Arnon, which was Moab's border. They never entered Moabite territory.
Then Israel asked Sihon king of the Amorites for passage through his land, but Sihon refused and attacked Israel at Jahaz. The Lord, the God of Israel, delivered Sihon and all his people into Israel's hand, and Israel possessed all the land of the Amorites from the Arnon to the Jabbok and from the wilderness to the Jordan. Jephthah argued that the Lord had dispossessed the Amorites before Israel, so Israel possessed that land. He asked the Ammonite king whether he would not possess what Chemosh his god gave him to possess, and said that whatever the Lord their God dispossessed before them, they would possess.
Jephthah reminded the Ammonite king that Balak of Moab had not fought against Israel when Israel dwelt in Heshbon and its towns for three hundred years. He asked why the Ammonites had not recovered the land in all that time if they had a claim. He declared that he had not sinned against the Ammonites, but they were doing wrong to war against Israel, and he called on the Lord, the Judge, to judge between Israel and Ammon that day. The king of the Ammonites did not listen.
Then the Spirit of the Lord came upon Jephthah, and he passed through Gilead and Manasseh and Mizpeh of Gilead and went toward the Ammonites. As he moved into battle, Jephthah made a vow to the Lord. He said that if the Lord would indeed deliver the Ammonites into his hand, then whatever came out of the doors of his house to meet him when he returned in peace would be the Lord's, and he would offer it up as a burnt offering.
The Lord delivered the Ammonites into Jephthah's hand. He struck them from Aroer to Minnith, twenty cities, and as far as Abel-cheramim, with a very great slaughter. The Ammonites were subdued before Israel.
When Jephthah came to his house at Mizpah, his daughter came out to meet him with timbrels and dances. She was his only child; he had no other son or daughter. When he saw her, he tore his clothes and cried out that she had brought him low and troubled him, because he had opened his mouth to the Lord and could not go back.
His daughter told him to do to her according to what had proceeded out of his mouth, since the Lord had taken vengeance on his enemies the Ammonites. She asked only that she be allowed two months to go down on the mountains with her companions and bewail her virginity. Jephthah sent her away for two months, and she and her companions bewailed her virginity on the mountains.
At the end of two months, she returned to her father, and he did to her according to his vow. She had never known a man. And it became a custom in Israel that the daughters of Israel went yearly to celebrate the daughter of Jephthah the Gileadite four days in a year.