Judges 11:30-40

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 1to the entrance of 2Minnith, 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 3Mizpah, behold, his daughter was coming out to meet him 4with 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 5given my word to the Lord, and 6I cannot take it back.” 36So she said to him, “My father, you have 7given your word to the Lord; 8do to me 9as 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 10go to the mountains and weep because of 11my 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 12had no relations with a man. Thus it became a custom in Israel, 40that the daughters of Israel went yearly to 13commemorate the daughter of Jephthah the Gileadite four days in the year.