How would the Lord have viewed Jephthah's offering ?
Judges 11:39 (ESV)
39And at the end of two months, she returned to her father, who did with her according to his vow that he had made. She had never known a man, and it became a custom in Israel
This offering was ambiguous. On the one hand, it was meant as a serious offering to the Lord. On the other hand, the vow was not as God had wanted to begin with, and consequently the offering cannot have pleased him.
39 And at the end of two months, she returned to her father, who did with her according to his vow that he had made. She had never known a man, and it became a custom in Israel