Eli answered, "Go in peace, and may the God of Israel grant you what you have asked of him." (1 Samuel 1:17)
More of a blessing rather than a promise; yet a promise to which Hannah held onto till she received what she had asked of God. She had spent years in mental anguish because the LORD had closed her womb and her rival (Elkanah's other wife Peninnah) kept provoking her in order to irritate her. Even the priest Eli thought she was drunk, when actually she was praying in her heart and only her lips were moving and her voice was not heard.
A blessing or a promise can change a depressed person's outlook fast. As soon as she heard Eli's reassuring words, she was filled with new hope, for the Bible says,
Then she went her way and ate something, and her face was no longer downcast. (1 Samuel 1:18)
In her misery Hannah had made a vow to the Lord:
"O LORD Almighty, if you will only look upon your servant's misery and remember me, and not forget your servant but give her a son, then I will give him to the LORD for all the days of his life, and no razor will ever be used on his head." (1 Samuel 1:11)
God blessed Hannah with a son whom she named Samuel. She kept her vow to the Lord and gave Samuel to the Lord's work as soon as he was weaned.
Eli would bless Elkanah and his wife, saying, "May the LORD give you children by this woman to take the place of the one she prayed for and gave to the LORD." Then they would go home. And the LORD was gracious to Hannah; she conceived and gave birth to three sons and two daughters. Meanwhile, the boy Samuel grew up in the presence of the LORD. (1 Samuel 2:20, 21)
Hannah's womb was closed by the Lord, but when he opened it, Hannah had 6 children. Our God is an awesome God. Praise be to his holy name.