Genesis 17:17

Then Abraham fell on his face, and laughed — It was a laughter of delight, not of distrust. Now it was that Abraham rejoiced to see Christ's day, now he saw it and was glad, John 8:56, for as he saw heaven in the promise of Canaan, so he saw Christ in the promise of Isaac, and said, Shall a child be born to him that is an hundred years old? — He doth not here speak of it, as at all doubtful, for we are sure he staggered not at the promise, Romans 4:20, but as wonderful, and that which could not be effected but by the almighty power of God.