Amos 4:5

“And offer a sacrifice of thanksgiving with leaven, etc.] Which some observe was contrary to the law, which forbids all leaven in a meat offering; or “burning” it in any offering, (<030211>Leviticus 2:11); which the wordf115 here used suggests was done by these idolaters, as well as eaten by them, their priests not liking to eat unleavened bread; but; though it was forbidden in the meat offering, was allowed, yea, ordered, with the sacrifice of thanksgiving, (<030713>Leviticus 7:13). So Abarbinel understands it here, as what was according, to law, but ironically commanded to be offered to idols: and proclaim [and] publish the free offerings; let all know of them when you make your freewill…”

“offer--literally, "burn incense"; that is, "offer a sacrifice of thanksgiving with burnt incense and with leavened bread." The frankincense was laid on the meat offering, and taken by the priest from it to burn on the altar (Lev 2:1-2, Lev 2:8-11). Though unleavened cakes were to accompany the peace offering sacrifice of animals, leavened bread was also commanded (Lev 7:12-13), but not as a "meat offering" (Lev 2:11). this liketh you--that is, this is what ye like.”

“And offer a sacrifice of thanksgiving with leaven - But amid this boastful service, all was self-will. In little or great, the calf-worship at Bethel, or the use of leaven in the sacrifice, they did as they willed. The prophet seems to have joined purposely the fundamental change, by which Jeroboam substituted the worship of nature for its God, and a minute alteration of the ritual, to show that one and the same temper, self-will, reigned in all, dictated all they did. The use of leaven in the things sacrificed was forbidden, out of a symbolic reason, that is, not in itself, but as representing something else. The Eastern leaven, like that used in France, consisting of what is sour, had the…”

“With leaven - As all the rest of your will - worship, so this also is against the express law, Lev 2:11. However, do so at your peril, try whether it will end in good. Proclaim - Publickly persuaded your people to voluntary sacrifices. Amos 4:6”

“4:5 Leavened bread (that is, sourdough fermented by wild yeast) was for daily consumption. The more primitive unleavened bread (made without yeast) became a sacred symbol, commemorating Israel’s affliction as slaves in Egypt (Deut 16:3), the Passover (Exod 12:17-20), and their hasty departure from that land (Exod 12:34, 39). Unleavened bread thus became altar bread (Lev 6:17; 7:12). However, bread made with yeast could accompany a peace offering of thanksgiving (Lev 7:13).”

“offer a sacrifice: Heb. offer by burning, Lev 7:12, Lev 7:13, Lev 23:17 proclaim: Lev 22:18-21; Deu 12:6, Deu 12:7; Mat 6:2 for: Psa 81:12; Mat 15:9, Mat 15:13, Mat 15:14, Mat 23:23; Rom 1:28; Th2 2:10-12 this liketh you: Heb. so ye love, Hos 9:1, Hos 9:10 Amos 4:6”