Cross reference
Genesis 21:5
5 Abraham was one hundred years old when his son, Isaac, was born to him.
Genesis 17:17
17 Then Abraham fell on his face, and laughed, and said in his heart, "Will a child be born to him who is one hundred years old? Will Sarah, who is ninety years old, give birth?"
Genesis 17:1
1 When Abram was ninety-nine years old, Yahweh appeared to Abram, and said to him, "I am God Almighty. Walk before me, and be blameless.
Romans 4:19
19 Without being weakened in faith, he didn't consider his own body, already having been worn out, (he being about a hundred years old), and the deadness of Sarah's womb.