Parallel
Judges 11:39
Brenton's English Septuagint · Berean Standard Bible
And it came to pass at the end of the two months that she returned to her father; and he performed upon her his vow which he vowed; and she knew no man:
After two months, she returned to her father, and he did to her as he had vowed. And she had never had relations with a man. So it has become a custom in Israel