5 And Abraam was a hundred years old when Isaac his son was born to him.
Genesis 21:5 Cross References - Brenton
Genesis 17:1
1 And Abram was ninety-nine years old, and the Lord appeared to Abram and said to him, I am thy God, be well-pleasing before me, and be blameless.
Genesis 17:17
17 And Abraam fell upon his face, and laughed; and spoke in his heart, saying, Shall there be a child to one who is a hundred years old, and shall Sarrha who is ninety years old, bear?