Judges 11:36-40

36“My father,” she replied, “you have given your word to the LORD . Do to me just as you promised, now that the LORD has avenged you of your enemies, the Ammonites.

37But grant me this one request,” she said. “Give me two months to roam the hills and weep with my friends, because I will never marry.” 38“You may go,” he said. And he let her go for two months. She and her friends went into the hills and wept because she would never marry.

39After the two months, she returned to her father, and he did to her as he had vowed. And she was a virgin. From this comes the Israelite tradition 40that each year the young women of Israel go out for four days to commemorate the daughter of Jephthah the Gileadite.