13 Now it was the practice of the priests that, whenever any of the people offered a sacrifice, the priest’s servant would come with a three-pronged fork in his hand while the meat was being boiled 14 and would plunge the fork into the pan or kettle or caldron or pot. Whatever the fork brought up the priest would take for himself. This is how they treated all the Israelites who came to Shiloh. 15 But even before the fat was burned, the priest’s servant would come and say to the person who was sacrificing, “Give the priest some meat to roast; he won’t accept boiled meat from you, but only raw.”
16 If the person said to him, “Let the fat be burned first, and then take whatever you want,” the servant would answer, “No, hand it over now; if you don’t, I’ll take it by force.”
17 This sin of the young men was very great in the Lord’s sight, for they were treating the Lord’s offering with contempt.
Eli’s sons were taking parts of the sacrifice before they offered it to God. Eli’s sons were treating God’s offerings with contempt. Eli’s sons were sinning while making the offerings. Offerings are to be given to show honor and respect to God while seeking forgiveness for sins. This demonstrates reverence to God. God will harshly judge those who lead his people astray or scorn what is devoted to him.