Her lamentations were of as little avail as her arguments with her father. In vain she sought to prove to him from the Torah that the law speaks only of animal sacrifices, never of human sacrifices. In vain she cited the example of Jacob, who had vowed to give God a tenth of all the possessions he owned, and yet did not attempt later to sacrifice one of his sons. Jephthah was inexorable.
All he would yield was a respite during which his daughter might visit various scholars, who were to decide whether he was bound by his vow. According to the Torah his vow was entirely invalid. He was not even obliged to pay his daughter's value in money. But the scholars of his time had forgotten this Halakah, and they decided that he must keep his vow.
The forgetfulness of the scholars was of God, ordained as a punishment upon Jephthah for having slaughtered thousands of Ephraim.