God spoke to Moses, saying: “Speak to the Israelites, saying: ‘As you recall, you may not eat any of the types of fat that constitute sacrificial fire-offerings, whether such fat be from an ox (or other bovine), a sheep, or a goat, and even if the specific animal is not offered up as a sacrifice but simply slaughtered to be eaten.
Furthermore, it will be explained later that when a permitted animal dies by any means other than properly performed ritual slaughter, or is discovered after slaughtering to have been suffering from a disease or injury from which it would have died had it not been slaughtered first, the flesh of this dead animal imparts ritual defilement. In contrast, the fat of carrion (i.e., of a permitted animal that died by any means other than ritual slaughter) and the fat of a ritually slaughtered animal with a fatal disease or injury does not impart ritual defilement, and therefore may be used for any type of work.
Nonetheless, even though you may use such fats, you must not eat them, both because (a) it is forbidden to eat sacrificial fat, as above, and because (b) it is forbidden to eat any part of carrion or of a fatally injured or diseased animal.
