Judges 11:39 in the King James Version
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,
Context
38 He said, “Go.” He sent her away for two months; and she departed, she and her companions, and mourned her virginity on the mountains.
39 At the end of two months, she returned to her father, who did with her according to his vow which he had vowed. She was a virgin. It became a custom in Israel
40 that the daughters of Israel went yearly to celebrate the daughter of Jephthah the Gileadite four days in a year.