Whence do we know about Ishmael? Because it is said, "And the angel of the Lord said unto her, Behold, thou art with child,… and thou shalt call his name Ishmael" (Gen. 16:11). Why was his name || called Ishmael? Because in the future the Holy One, blessed be He, will hearken to the cry of the people arising from (the oppression) which the children of Ishmael will bring about in the land in the last (days); therefore was his name called Ishmael.
Whence do we know about Moses? Because it is said, "And the Lord said, My spirit shall not abide in man for ever in their going astray" (Gen. 6:3). What is the implication (of the expression), "In their going astray"? Retrospectively his name was called Moses. For the life of Moses was one hundred and twenty years, as it is said, "His days shall be an hundred and twenty years" (ibid.).