Even before the fat was burned, the servant of the priest would come and say to the man who was sacrificing, "Give the priest some meat to roast, because he will not accept boiled meat from you, but only raw." And if any man said to him, "The fat must be burned first; then you may take whatever you want," the servant would reply, "No, you must give it to me right now. If you refuse, I will take it by force!" Thus the sin of these young men was severe in the sight of the LORD, for they were treating the LORD's offering with contempt.
Then the priest is to burn the food on the altar as an offering made by fire, a pleasing aroma. All the fat is the LORD's. This is a permanent statute for the generations to come, wherever you live: You must not eat any fat or any blood."
Significance
Leviticus 3:16-17 establishes the perpetual statute (חֻקַּת עוֹלָם, chuqqat olam): "All the fat is the LORD's" and "You must not eat any fat or any blood." The fat and blood of the peace offering constitute YHWH's inviolable share. In 1 Samuel 2:15-17, Eli's sons systematically violate this statute by demanding raw meat before the fat is burned, treating the LORD's portion with contempt (וַיִּנְאֲצוּ, vayin'atsu). The narrator explicitly states their sin was "severe in the sight of the LORD" precisely because it transgressed the Levitical regulation that the fat must be burned to YHWH first, making their priestly corruption a direct assault on the sacrificial order God established. The offense included overt coercion: when a worshiper insisted the fat be burned first, the priest's servant threatened to take the meat by force (1 Samuel 2:16), turning ritual violation into naked intimidation of the worshiper.
