Unlike the popular Abraham and Isaac in which an angel of God released Abraham from sacrificing his son, the story of Jepthah's daugther is left to be forgotten. The events surrounding Jepthah can be found in Judges 10:6:, 12:7 .The story of his daughters sacrifice is covered in Judges 11:29-40
Contrary to Apologists for God, Jepthah actually fulfilled his vow and sacrificed his daughter.
Jepthah was probably hoping his wife or mother-in-law would be the first to come out to greet him, but no such luck.
This cultic behavior and thinking but given a pass because a Bronze Age author tells us the voices in the heads of these characters was really God and this we are to take on faith.
That's not how "prove me now herewith" works, in the real world of critical thinking and common sense.