Genesis 21:8

And the child grew and was weaned. And Abraham made a great feast the same day that Isaac was weaned. So Abraham shared the grateful joy of his wife, making the occasion of his son's weaning a great festival, with the customary feast. This happened when Isaac was about three years old. This story reminds us of the greater miracle of the birth of Jesus, who also, but in a far more wonderful manner, was born contrary to the course of nature. Isaac, too, is a type of the believers of all time. For just as he was born by virtue of the divine promise, so we are spiritual children of the promise, Romans 9:8; Galatians 4:28; 1 Peter 1:23.