Then Abraham fell upon his face, and laughed, and said in his heart, Shall a child be born unto him that is a hundred years old? and shall Sarah, that is ninety years old, bear?
All Commentaries on Genesis 17:17 Go To Genesis 17
Cyril of Alexandria
AD 444
: He was not laughing because he did not believe, as some might imagine, but rejoicing because he did. “He laughed” is sometimes put in place of “he rejoiced,” as it is also in the Gospels. And for this reason, he also “fell on his face” and marveled in his heart.