Judges 11:30, 31, 35 And Jephthah vowed a vow unto the Lord, and said, If thou shalt without fail deliver the children of Ammon into mine hands, Then it shall be that whatsoever cometh forth of the doors of my house to meet me, when I return in peace from the children of Ammon, shall surely be the Lord’s, and I will offer it up for a burnt offering….And it came to pass, when he saw her, that he rent his clothes, and said, Alas, my daughter! Thou hast brought me very low for I have opened my mouth unto the Lord, and I cannot go back.
Israel was being oppressed by the Ammonites, and when they cried to the Lord, He sent the Spirit upon Jephthah to deliver them and become their judge. Jephthah wisely prayed to the Lord to be with him and grant victory. But Jephthah foolishly vowed a vow that he would keep if God answered his prayer. He vowed that whatever came out of the door of his house when he returned home he would sacrifice to the Lord. His daughter appeared first, and he had to fulfill his vow. Even the daughter agreed that he couldn’t go back on his word. She asked for two months with her companions before being sacrificed.
We are meant to see how seriously we should take our vows to the Lord. It also applies to our promises to people. A faithful man keeps his promises. Therefore, we must carefully consider before making any vows at all. It is good and proper to make some vows, and keep them: marriage vows, confirmation vows to be faithful, legal contracts (like credit), and vows to tell the truth in a court of law. Other than that, any other rash or frivolous vow should not be made, but if so, like Jephthah, it must be kept.
We are sometimes tempted to bargain with God in order to get Him to answer our prayer, so we make a foolish vow. Wrong thinking! God answers because He promised to for Jesus’ sake, and not because we make a vow or promise, indeed, not because of anything in us. Be careful in making a promise, for a man of his word will have to keep it.