Prov 20:25
It is a trap for a man to dedicate something rashly and only later to consider his vows.
Too bad Jephthah didn’t have knowledge of this proverb when he made his rash promise.

Judg 11:31-32
whatever comes out of the door of my house to meet me when I return in triumph from the Ammonites will be the LORD's, and I will sacrifice it as a burnt offering." Then Jephthah went over to fight the Ammonites, and the LORD gave them into his hands.

Judg 11:34-35
When Jephthah returned to his home in Mizpah, who should come out to meet him but his daughter, dancing to the sound of tambourines! She was an only child. Except for her he had neither son nor daughter. When he saw her, he tore his clothes and cried, "Oh! My daughter! You have made me miserable and wretched, because I have made a vow to the LORD that I cannot break."

The following proverb is a great companion piece to the admonition for parents in Deuteronomy.
Prov 6:20-23
My son, keep your father's commands and do not forsake your mother's teaching. Bind them upon your heart forever; fasten them around your neck. When you walk, they will guide you; when you sleep, they will watch over you; when you awake, they will speak to you. For these commands are a lamp, this teaching is a light, and the corrections of discipline are the way to life,

Deut 6:6-9
These commandments that I give you today are to be upon your hearts. Impress them on your children. Talk about them when you sit at home and when you walk along the road, when you lie down and when you get up. Tie them as symbols on your hands and bind them on your foreheads. Write them on the doorframes of your houses and on your gates.

Do we take to heart these Scriptures? Do we impress them on our children? Do we bind them on our heart? Do His words guide us? Are His words so much a part of our lives that they guide us even when we sleep?