Psalm 76:11 (NASB)
Make vows to the Lord your God and fulfill them;
Let all who are around Him bring gifts to Him who is to be feared.

Commentary
We need to be people of integrity that keep our word to the best of our ability. We also need to realize that there are at times that circumstances get in our way.So we need to also be gracious to those who at times seem to not be faithful to their word. That of course, why we should be careful what we promise.