Judges 11:38

³⁶And she said to him, Father, hast thou opened thy mouth to the Lord? Do to me accordingly as the word went out of thy mouth, in that the Lord has wrought vengeance for thee on thine enemies of the children of Ammon.

³⁷And she said to her father, Let my father now do this thing: let me alone for two months, and I will go up and down on the mountains, and I will bewail my virginity, I and my companions.

— Judges 11:38 —

³⁹And it came to pass at the end of the two months that she returned to her father; and he performed upon her his vow which he vowed; and she knew no man:

⁴⁰and it was an ordinance in Israel, That the daughters of Israel went from year to year to bewail the daughter of Jephthah the Gileadite for four days in a year.