Genesis 17:1, 17
When Abram was ninety-nine years old, the LORD appeared to him and said, "I am God Almighty. Walk before Me and be blameless. . . .

Genesis 12:4
So Abram departed, as the LORD had directed him, and Lot went with him. Abram was seventy-five years old when he left Haran.

Romans 4:11, 19, 20
And he received the sign of circumcision as a seal of the righteousness that he had by faith while he was still uncircumcised. So then, he is the father of all who believe but are not circumcised, in order that righteousness might be credited to them. . . .