Keep your Vows - Leviticus 25-27

 Leviticus 27:28-29 (ESV)
“But no devoted thing that a man devotes to the LORD, of anything that he has, whether man or beast, or of his inherited field, shall be sold or redeemed; every devoted thing is most holy to the LORD. No one devoted, who is to be devoted for destruction from mankind, shall be ransomed; he shall surely be put to death.

Leviticus 27:21 (ESV)
But the field, when it is released in the jubilee, shall be a holy gift to the LORD, like a field that has been devoted. The priest shall be in possession of it.

God takes what we vow very seriously.    When we vow to raise our children for Him and dedicate them to Him, He takes us at our word.  If after that dedication we try to take those children back, God counts that a breaking a vow.  That is the context for the above verses.   Verses 28 and 29 are a continuation of verse 21.   The illustration used is not about children but about a piece of land.  But, the principle is the same.  God counts our vows as His.   It is in reverence we should vow.  It is in reverence we should keep a vow.  Notice what Solomon would say about vows, years later than this passage:

Ecclesiastes 5:2-6 (ESV)
Be not rash with your mouth, nor let your heart be hasty to utter a word before God, for God is in heaven and you are on earth. Therefore let your words be few. For a dream comes with much business, and a fool's voice with many words.
When you vow a vow to God, do not delay paying it, for he has no pleasure in fools. Pay what you vow. It is better that you should not vow than that you should vow and not pay. Let not your mouth lead you into sin, and do not say before the messenger that it was a mistake. Why should God be angry at your voice and destroy the work of your hands?

God is concerned about what we vow.   We do ourselves harm and hinder our relationship with Him when we do not keep the vows we made to Him.