With leaven — As all the rest of your will — worship, so this also is against the express law, Leviticus 2:11. However, do so at your peril, try whether it will end in good. Proclaim — Publickly persuaded your people to voluntary sacrifices.
Related Commentaries of Amos 4:5
Amos 4:5
5 And offerc a sacrifice of thanksgiving with leaven, and proclaim and publish the free offerings: for this liketh you, O ye children of Israel, saith the Lord GOD.