Judges 11:38-42

And he said, Go. And he sent her away for two months: and she went with her companions, and bewailed her virginity upon the mountains.

And it came to pass at the end of two months, that she returned unto her father, who did with her according to his vow which he had vowed: and she knew no man. And it was a custom in Israel,

That the daughters of Israel went yearly to lament the daughter of Jephthah the Gileadite four days in a year.