And he said, Go. And he sent her away for two months: and she went with her companions, and lamented her virginity upon the mountains.
Read Chapter 11
Augustine of Hippo
The Scriptures do not seem to pass judgment on this vow and its fulfillment as it does quite clearly in the case of Abraham, when he was ordered to sacrifice his son and did so. Rather the Scriptures seem to have only recorded the matter and left it to the reader to evaluate, just as in the case of Judah, Jacob’s son, who in ignorance lay with his daughter-in-law but committed fornication by the very act, because he thought her to be a prostitute. The Scriptures never approve nor disapprove of the act explicitly but let the matter stand, to be evaluated and contemplated after consulting the righteousness and law of God. Therefore, the Scriptures of God do not offer any comment in either the vow or its fulfillment, so that our mind might be put to work to pass judgment on this matter and so that we might now say that such a vow displeased God and led to the punishment that his only daughter, of all people, ran out to meet her father. - "Questions on Judges 49.7"
Mountains. Such places were frequented in times of mourning, Jeremias xxxi. 15., and Isaias xv. 2. (Calmet)
Jepthe allowed his daughter this short respite, without any offence, (Deuteronomy xxiii. 21,) before he immolated her, (Menochius) or before he debarred her from the society of men. (Grotius)