Judges 11:38-40

New Living Translation

³⁸ “You may go,” Jephthah said. And he sent her away for two months. She and her friends went into the hills and wept because she would never have children. ³⁹ When she returned home, her father kept the vow he had made, and she died a virgin.

So it has become a custom in Israel ⁴⁰ for young Israelite women to go away for four days each year to lament the fate of Jephthah’s daughter.