Related for Chullin 186:59

Rebbi Eleazar in the name of Rebbi Hoshaiah: It is a condition imposed by the Court that the fat²⁰⁶That fat of a four-legged animal, which in a sacrifice would go on the altar, is forbidden for profane use (Lev. 3:17). It has to be cut out before the piece of meat is sold. be on the butcher and the sciatic tendon²⁰⁷It may not be eaten (Gen. 32:33). It must be cut out together with all the fat in which it is embedded. The butcher would naturally cut out only the minimum of fat in order to maximize his profit. on the buyer. Rebbi Abbahu made it common usage in Caesarea that both should be on the buyer, so that they would amply take out.