²⁹ Then the Spirit of the Lord came on Jephthah and he passed through Gilead and Manasseh, and passed through Mizpah of Gilead, and went on to the Ammonites. ³⁰ Jephthah made a vow to the Lord, “If You will indeed give the Ammonites into my hands, ³¹ then whatever comes out from the door of my house to meet me, when I return safely from the Ammonites, will surely be the Lord’s, and I will offer it up as a burnt offering.”

³² So Jephthah crossed over to the Ammonites to wage war against them, and the Lord gave them into his hands. ³³ He struck them down from Aroer to Minnith, twenty cities, and as far as Abel Keramim. The defeat was very severe, and the Ammonites were humbled before the children of Israel.

³⁴ When Jephthah went to his house at Mizpah, there was his daughter coming out to meet him, dancing with a tambourine. She was his only child. Other than her, he had neither son nor daughter. ³⁵ When he saw her, he ripped up his clothes and said, “Alas, my daughter! You have brought utter disaster to me. You are my undoing, for I have given my word to the Lord, and I cannot take it back.”

³⁶ She said to him, “My father, you have opened your mouth to the Lord. Do to me what has come out of your mouth, because the Lord worked vengeance upon your enemies, the Ammonites.” ³⁷ Then she said to her father, “Let this be done for me: Give me two months, and I and my friends will wander the hill country and mourn over my virginity.”

³⁸ He said, “Go,” and he sent her away for two months. She and her friends went and mourned over her virginity in the hill country. ³⁹ At the end of two months she returned to her father, and he did to her according to the vow that he had made. She had not ever slept with a man.

So it became a custom in Israel ⁴⁰ that the women of Israel would commemorate the daughter of Jephthah the Gileadite for four days each year.