Judges 11:31-39

31then whatever comes out of the doors of my house to meet me when I return safely from Ammon will belong to the Lord. I will sacrifice it as a burnt offering.”

32So Jephthah went to fight against Ammon. The Lord handed the people of Ammon over to him.

33He defeated them from Aroer to Minnith and on to Abel Keramim, 20 cities in all. It was a decisive defeat. So the Ammonites were crushed by the people of Israel.

34When Jephthah went to his home in Mizpah, he saw his daughter coming out to meet him. She was dancing with tambourines in her hands. She was his only child. Jephthah had no other sons or daughters.

35When he saw her, he tore his clothes in grief and said, “Oh no, Daughter! You’ve brought me to my knees! What disaster you’ve brought me! I made a foolish promise to the Lord. Now I can’t break it.”

36She said to him, “Father, you made a promise to the Lord. Do to me whatever you promised since the Lord has punished your enemy Ammon.”

37Then she said to her father, “Do me a favor. Give me two months for my friends and me to walk in the mountains and mourn that I will never have an opportunity to get married.”

38“Go!” he said, and he sent her off for two months. She and her friends went to the mountains, and she cried about never being able to get married.

39At the end of those two months she came back to her father. He did to her what he had vowed, and she never had a husband. So the custom began in Israel