Genesis 16:11
And the angel of the LORD said unto her, Behold, thou art with child, and shalt bear a son, and shalt call his name Ishmael; because the LORD hath heard thy affliction. And the angel of the LORD said unto her, Behold, thou art with child, and shalt bear a son, and shalt call his name Ishmael; because the LORD hath heard thy affliction.
The angel's announcement told Hagar that she was with child and would bear a son, expressly because the Lord had heard her affliction. The son was to be called Ishmael, a name meaning God shall hear. That name was given as a lasting reminder of God's mercy shown to her in her suffering.