Charles Ellicott Commentary Amos 4:5

"and offer a sacrifice of thanksgiving of that which is leavened, and proclaim freewill-offerings and publish them: for this pleaseth you, O ye children of Israel, saith the Lord Jehovah." — Amos 4:5 (ASV)

The margin is more correct, and gives the key to the passage. Render, and offer by burning your thank-offering of leaven. Leaven was not allowed in any sacrifice offered by fire. Amos ironically calls upon them to break the Levitical law (Leviticus 7:13; Leviticus 23:17), as he knew they were in the habit of doing.