'Vow' in the Bible

And Jephthah vowed a vow unto the LORD, and said, If thou shalt without fail deliver the children of Ammon into mine hands,

And when he saw her, he rent his clothes, and said, "Alas, my daughter! you have brought me very low, and you have become the cause of great trouble to me; for I have opened my mouth to the LORD, and I cannot take back my vow."

And it came to pass at the end of two months, that she returned unto her father, who did with her according to his vow which he had vowed: and she knew no man. And it was a custom in Israel,

Now the people of Israel had taken a vow in Mizpah that went like this: "Not even one of us will give his daughter in marriage to a descendant of Benjamin!"

But we can't give them wives from our own daughters, since we've taken this vow: "May the LORD curse anyone who gives his daughter as a wife to the tribe of Benjamin!'"