Judges 11:38

34 Jephthah came to Mizpah to his house; and, behold, his daughter came out to meet him with tambourines and with dances: and she was his only child; besides her he had neither son nor daughter.

35 It happened, when he saw her, that he tore his clothes, and said, Alas, my daughter! you have brought me very low, and you are one of those who trouble me; for I have opened my mouth to Yahweh, and I can`t go back.

36 She said to him, My father, you have opened your mouth to Yahweh; do to me according to that which has proceeded out of your mouth, because Yahweh has taken vengeance for you on your enemies, even on the children of Ammon.

37 She said to her father, Let this thing be done for me: let me alone two months, that I may depart and go down on the mountains, and bewail my virginity, I and my companions.

38 He said, Go. He sent her away for two months: and she departed, she and her companions, and mourned her virginity on the mountains.

39 It happened at the end of two months, that she returned to her father, who did with her according to his vow which he had vowed: and she was a virgin. It was a custom in Israel,

40 that the daughters of Israel went yearly to celebrate the daughter of Jephthah the Gileadite four days in a year.