Judges 11:34-40

With God's help, the Ammonites were subdued with a great slaughter. Jephthah's daughter, who was his only child, was the first to come out of his house to greet him and celebrate his victory with dancing (Compare Exodus 15:20; 1 Samuel 18:6-7). Ordinarily, a father would rejoice to see his child running out to meet him upon his return home. However, because of the vow he had made to God, Jephthah tore his clothes and cried out.

His daughter considered a vow to the Lord to be so important that she told her father to do to her whatever he had promised. Her one request was that she be allowed to go to the mountains and bewail her virginity because she would never know a man. When the time was up, Jephthah kept his vow. From that day forward, the young women of Israel devoted four days a year to go to the mountains and sing praises for Jephthah's daughter (Ruth 11:34-40).

Leviticus 27:28 speaks of devoted offerings to the Lord, which may well explain Hannah's vow to the Lord in reference to Samuel prior to his conception (1 Samuel 1:8-11). However, God despised the human sacrifices the nations made to Molech (Leviticus 18:21; Leviticus 20:1-5; Deuteronomy 12:29-31). What then are we to do with a man of faith making a vow that would cause him to do the very thing God hated (Hebrews 11:32)? Keil suggests the vow could have been fulfilled in a spiritual sense with the girl remaining unmarried and her being dedicated to God for the rest of her life. If we cannot accept that idea, it would appear we must think of this as one of the flaws found in a man who otherwise served God well. The importance of keeping one's promises to God would still be seen in the midst of a terrible sin.