Charles Ellicott Commentary Exodus 29:14

"But the flesh of the bullock, and its skin, and it dung, shalt thou burn with fire without the camp: it is a sin-offering." — Exodus 29:14 (ASV)

The flesh ... shalt thou burn ... without the camp. (Leviticus 4:21; Hebrews 13:11–13). This was the general rule with sin offerings. The whole animal was considered too impure for any portion of it to be suitable for human food.

His dung. — What the intestines contained at the time of death.