Vows were a common practice in Israel. If a person had a special concern that he brought to Yahweh, he would often promise to do something in return as a way of giving thanks. They were not required to, but if a vow was made, fulfillment was required (Deut.23:21-23). Jephthah promised to offer to God the first thing that came out of his house, if Yahweh would give him success in battle.
Victory was given, and the first thing to exit the house was Jephthah’s only
child, his daughter, whom he sacrificed (vv. 31, 39).
There are two general principles that need to be mentioned here. First, it is never proper to make a vow about something that is forbidden by God.
That is sin. Jephthah should have seen the possibility that a human could be the first out of the house, and sacrificing a person is sin. Second, while making vows is not wrong, be very careful what you vow. It is better not to vow than to vow and not fulfill it (Eccl.5:4-5). However, Jesus offered Himself to the Father as payment for human sin, a payment that was well-received.
Meditate on verses 34-35. What is God teaching you in these verses?
Merciful Father, in the name of Jesus Christ, draw me close to You in
order to enhance my trust in You and teach me to avoid unnecessary
vows including swearing in your Holy Name. Amen.