Be careful what you promise in prayer because God may take you up on it. Hannah so desperately wanted a child that she was willing to strike a bargain with God. God took her up on her promise, and to Hannah’s credit, she did her part, even though it was painful. Although we are not in a position to barter with God, he may still choose to answer a prayer that has an attached promise. When you pray, ask yourself: “Will I follow through on any promises I make to God if he grants my request?” It is dishonest and dangerous to ignore a promise, especially to God. God keeps his promises, and he expects you to keep yours.
Source: My Reading plan on youversion