Charles Ellicott Commentary 1 Samuel 2:15

"Yea, before they burnt the fat, the priest`s servant came, and said to the man that sacrificed, Give flesh to roast for the priest; for he will not have boiled flesh of thee, but raw." — 1 Samuel 2:15 (ASV)

Before they burned the fat. —This was an even graver offense against the ritual of the sacrifice. A contemptuous insult was offered here to the Lord. This fat was not to be eaten or taken by anyone; it was God’s portion, to be burned by the priest on the altar (Leviticus 3:16; Leviticus 7:23; Leviticus 7:25; Leviticus 7:30–31).

In all these strange rites and ceremonies, there was a higher symbolism involved. This was ruthlessly disregarded and trampled on by these reckless, covetous guardians of Israel’s worship.

Portions of the sacrifice legally fell to the ministering priests in lieu of a fee. It was fair that they which ministered at the altar should live of the altar. The “heave leg” and the “wave breast” of the slaughtered victim were theirs by right, and the sacrificing priest was to receive these after the fat portion of the sacrifice had been burned upon the altar. But to take the flesh of the victim and roast it before the symbolic offering had been made was a crime equivalent to robbing God. It dishonored the whole ceremony.

He will not have sodden flesh. —The meaning of this is that these priests and their attendants insisted on having the best part of the sacrificed victim raw, not boiled—that is, fresh, full of juice and strength—before the offering had been made.