Judges 11:34-40 - Jephthah's Daughter
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 given my word to the LORD, and I can't break it."
36 She said to him, "My father, since you have given your word to the LORD; do to me as you promised, because the LORD 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: leave me alone two months, that I may depart and go down on the mountains, and weep because of 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 wept because of 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 what he had vowed. And she was a virgin. It became a custom in Israel, 40 that the daughters of Israel went yearly four days in a year to commemorate the daughter of Jephthah the Gileadite.