Bless their hearts, Israel couldn’t stay focused on God, and would turn from him to chase after the gods of other countries. It seems interesting that they knew to go back to him and beg for his help. At one point God had had enough and told them, “Yet you have forsaken me, and served other gods; therefore I will save you no more.” However, Israel cleaned up their act, got rid of the other gods, and because God couldn’t stand seeing them oppressed any longer, he sent Jephthah to fight for them. Jephthah had the spirit of God upon him, but made a vow to God that if he won this battle, he would sacrifice the first thing that came out of his door, but unfortunately it was his only child, his daughter. God gave Jephthah victory, and so he kept his vow.
Do not make a vow to God that you can’t keep! We’ve all probably said things like, “God, if you’ll get me out of this, I will not________________again.” If that is the case for you, you had better keep your vow, otherwise keep your mouth shut, God doesn’t take these things lightly. Be careful of any words you speak over yourself; remember that the devil hears them too. (Judges 11)
"Be not rash with your mouth, nor let your heart be hasty to utter a word before God, for God is in heaven and you are on earth. Therefore let your words be few." Ecclesiastes 5:2