How old was Isaac when he was weaned?
Isaac was five years old when he was weaned. The passage records that the child grew and was weaned, and Abraham made a great feast the same day. This event is placed chronologically at age five, which would make Ishmael about eighteen or nineteen.
Les explains that chronologically Isaac had to be five years old when he was weaned. That timing places Ishmael at about eighteen or nineteen—no longer a little child but at the end of his teen years. In the account, the child grew and was weaned, and Abram made a great feast the same day that Isaac was weaned. Earlier, Sarah had said God made her laugh, and Isaac's name meant laughter.