Why Abraham Needed No Periah but Ishmael Did at Circumcision

"When the flesh of his foreskin was circumcised." Concerning Abraham it is written, "when the flesh of his foreskin was circumcised," and concerning Ishmael it is written, "the flesh of his foreskin" (verse 14). Abraham, because he had taken a wife and had marital relations, had no [excess] skin, and did not require periah (the uncovering). But Ishmael, who was a youth and had not yet had marital relations, still had [excess] skin that required periah.