Charles Spurgeon Commentary Leviticus 16:26-27

"And he that letteth go the goat for Azazel shall wash his clothes, and bathe his flesh in water, and afterward he shall come into the camp. And the bullock of the sin-offering, and the goat of the sin-offering, whose blood was brought in to make atonement in the holy place, shall be carried forth without the camp; and they shall burn in the fire their skins, and their flesh, and their dung." — Leviticus 16:26-27 (ASV)

All must be burned; and the last is mentioned because it more strikingly shows the impurity of the sin connected with the sin offering. All must be burned completely; there must not be a particle of the sin offering left unconsumed.