'Vow' in the Bible

Jephthah made a vow to the Lord and said, “If You will indeed give the Ammonites into my hand,

And when he saw her, he tore his clothes [in grief] and said, “Alas, my daughter! You have brought me great disaster, and you are the cause of ruin to me; for I have made a vow to the Lord, and I cannot take it back.”

At the end of two months she returned to her father, who did to her as he had vowed; and she had no relations with a man. It became a custom in Israel,