Stories in the Bible don’t always have a “happily ever after” ending. The story of Jephthah and his daughter is one of those stories that is both shocking and confusing. Jephthah made a rash bargain with God. If God would allow him victory against his enemies, he would sacrifice the first thing that came out of his house. Unfortunately, it was his daughter that came out of the house to meet him. How could a man make such a promise?

Equally shocking and confusing is that Jephthah’s daughter also honored her father’s bargain.
What does God say about such a bargain?

Eccl 5:4-6a
When you make a vow to God, do not delay in fulfilling it. He has no pleasure in fools; fulfill your vow. It is better not to vow than to make a vow and not fulfill it. Do not let your mouth lead you into sin.

Leviticus and Deuteronomy list rules pertaining to vows of dedication.
Deut 23:21-23
If you make a vow to the LORD your God, do not be slow to pay it, for the LORD your God will certainly demand it of you and you will be guilty of sin. But if you refrain from making a vow, you will not be guilty. Whatever your lips utter you must be sure to do, because you made your vow freely to the LORD your God with your own mouth.

This passage is very clear that such vows are not from the Lord. They are from the mouth of men. Lessons for us are equally clear. We must be very cautious in making vows to the Lord.