Jamieson, Fausset and Brown on Hosea 12:7

7. 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 Is 23:11, Margin), the greatest reproach to Israel, who despised Canaan. The Phoenicians called themselves Canaanites or merchants (Is 23:8).

oppress--open violence: as the "balances of deceit" imply fraud.