How do we know Jephthah's act was of faith?

The writer of Hebrews cites Jephthah in the 'Hall of Faith' as a commendation of his actions, framing them as a demonstration of faith amidst a troubling narrative. This assertion challenges differing interpretations that label his vow as foolish or rash. By placing Jephthah in this context, scripture implies that his commitment to fulfill his vow, even to the most extreme extent, was aligned with his faith in God’s sovereignty and ability to deliver. This aspect is critical in understanding Jephthah's character and his plight, showing that God honors faith even in complex situations.