Shofetim 11:38-40

Orthodox Jewish Bible

³⁸ And he said, Go. And he sent her away for two chodashim; and she went with her companions, and bewailed her betulim (virginity) upon the hills.

³⁹ And it came to pass at the end of two chodashim, that she returned unto her av, who did with her according to his neder which he had vowed; and she knew no man. And it was a chok in Yisroel,

⁴⁰ That the banot Yisroel went yearly to lament the bat Yiftach the Gileadi arba’at yamim bashanah.