Judges 11:37-39

New Living Translation

³⁷ But first let me do this one thing: Let me go up and roam in the hills and weep with my friends for two months, because I will die a virgin.”

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