Charles Ellicott Commentary Leviticus 4:11

"And the skin of the bullock, and all its flesh, with its head, and with its legs, and its inwards, and its dung," — Leviticus 4:11 (ASV)

And the skin of the bullock. —Unlike other burnt offerings, whose skins were taken off and became the perquisite of the priests (Leviticus 7:8), this sin offering was not flayed at all, but was cut to pieces with its skin.