Chapter 16 / Where did you come from, where did you go?

וקראת שמו AND THOU SHALT CALL — This is a command, just as one would say to a man (וְקָרָאתָ), as (Genesis 17:19) “And thou shalt call his name Isaac”.

AND THOU SHALT CALL HIS NAME ISHMAEL. The angel informed Hagar that his name will be Ishmael — just as in the verse, Behold, a son shall be born unto the house of David Josiah by name — and he told her that she should so call him, and thus remember that G-d heard her affliction. Now Abraham either called him by this name on his own, with the intent that G-d hear him and answer him, or the Holy Spirit rested upon him, as Rashi has it, and he called him Ishmael because G-d had heard his mother’s affliction, as the angel had said.
The correct interpretation appears to me to be that the angel commanded Hagar that she call him so, but she, being a concubine, was afraid to give a name to her master’s son, so she revealed the matter to him, and Abram fulfilled the word of G-d. Scripture, however, did not need to delve at length into this matter.