5 And Abraham was one hundred years old when his son Isaac was born unto him.
Genesis 21:5 Cross References - EJ2000
Genesis 17:1
1 ¶ And when Abram was ninety-nine years old, the LORD appeared to Abram and said unto him, I am the Almighty God; walk before me and be thou perfect.
Genesis 17:17
17 Then Abraham fell upon his face and laughed and said in his heart, Shall a child be born unto him who is one hundred years old? and shall Sarah, who is ninety years old, bear?
Romans 4:19
19 And he did not weaken in faith: he considered not his own body now dead when he was about one hundred years old, neither yet the deadness of Sara’s womb;