Judges 11:36-40

So she said to him, “My father, you have given your word to the Lord; do to me just as you have said, since the Lord has brought you vengeance on your enemies, the sons of Ammon.”

And she said to her father, “Let this thing be done for me; allow me two months, so that I may go to the mountains and weep because of my virginity, I and my friends.”

Then he said, “Go.” So he let her go for two months; and she left with her friends, and wept on the mountains because of her virginity.

And at the end of two months she returned to her father, who did to her what he had vowed; and she had no relations with a man. And it became a custom in Israel,

that the daughters of Israel went annually to commemorate the daughter of Jephthah the Gileadite for four days in the year.