merchant - a play on the double sense of the Hebrew, “Canaan,” that is, a Canaanite and a “merchant” Eze 16:3 : “Thy birth is ... of Canaan.” They who naturally were descendants of pious Jacob had become virtually Canaanites, who were proverbial as cheating merchants (compare Isa 23:11, Margin), the greatest reproach to Israel, who despised Canaan. The Phoenicians called themselves Canaanites or merchants (Isa 23:8).
oppress - open violence: as the “balances of deceit” imply fraud.