then it shall be, that whatever comes forth from the doors of my house to meet me, when I return in peace from the children of Ammon, it shall be Yahweh's, and I will offer it up for a burnt offering.
Jephthah made a vow before going into battle. He promised that if the Lord would give him victory he would give God whatever came out of the door of his house when he returned from the conflict (Judges 11:30-31). He would offer this person or animal either as a sacrifice of dedication to the Lord or as a burnt offering of worship (Judges 11:31).