Judges 11:37-39

Modern English Version

³⁷ Then she said to her father, “Let this be done for me: Give me two months, and I and my friends will wander the hill country and mourn over my virginity.”

³⁸ He said, “Go,” and he sent her away for two months. She and her friends went and mourned over her virginity in the hill country. ³⁹ At the end of two months she returned to her father, and he did to her according to the vow that he had made. She had not ever slept with a man.

So it became a custom in Israel