We see that Hannah was also true to her word and when the child was of age, she took him to the house of the Lord and left him there with Samuel the priest. How hard it must have been for Hannah to leave her boy that she had prayed so long for. But she made a promise to God and she intended to keep her word.
Have you ever told the Lord that if he did a certain something for you that you would do something in return? If you have, did you keep your promise? Were you true to your word? We should never make a promise to God if we know we might not be able to keep it. Be very careful. So many people have made promises that they have never kept. God is not to be mocked or made little of. Be very sure that you can do what you promise. If your not sure you can, don't promise anyone anything, especially God.