TSK · Genesis 17:24

So Abram went, as Yahweh had spoken to him. Lot went with him. Abram was seventy-five years old when he departed out of Haran.

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?"

Abraham was one hundred years old when his son, Isaac, was born to him.

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.