Judges 11:29-40

²⁹Now the Spirit of the Lord came upon Jephthah, so that he passed through Gilead and Manasseh; then he passed through Mizpah of Gilead, and from Mizpah of Gilead he went on to the sons of Ammon. ³⁰Jephthah made a vow to the Lord and said, “If You will indeed give the sons of Ammon into my hand, ³¹then it shall be that whatever comes out of the doors of my house to meet me when I return in peace from the sons of Ammon, it shall be the Lord’s, and I will offer it up as a burnt offering.” ³²So Jephthah crossed over to the sons of Ammon to fight against them; and the Lord gave them into his hand. ³³He struck them with a very great slaughter from Aroer to the entrance of Minnith, twenty cities, and as far as Abel-keramim. So the sons of Ammon were subdued before the sons of Israel.

³⁴When Jephthah came to his house at Mizpah, behold, his daughter was coming out to meet him with tambourines and with dancing. Now she was his one and only child; besides her he had no son or daughter. ³⁵When he saw her, he tore his clothes and said, “Alas, my daughter! You have brought me very low, and you are among those who trouble me; for I have given my word to the Lord, and I cannot take it back.” ³⁶So she said to him, “My father, you have given your word to the Lord; do to me as you have said, since the Lord has avenged you of your enemies, the sons of Ammon.” ³⁷She said to her father, “Let this thing be done for me; let me alone two months, that I may go to the mountains and weep because of my virginity, I and my companions.” ³⁸Then he said, “Go.” So he sent her away for two months; and she left with her companions, and wept on the mountains because of her virginity. ³⁹At the end of two months she returned to her father, who did to her according to the vow which he had made; and she had no relations with a man. Thus it became a custom in Israel, ⁴⁰that the daughters of Israel went yearly to commemorate the daughter of Jephthah the Gileadite four days in the year.