In the eighth chapter of Amos is a recording of disdain for greedy merchants.

vs.5 Saying, when will the New Moon be gone, that we may sell corn? and the Sabbath, that we may set forth wheat, making the ephah small, and the shekel great, and falsifying the balances by deceit?

Even greedy merchants who cheat their customers would not violate the Sabbath by conducting business on this day. This proscription against transacting business on the Sabbath is also noted by the prophet Amos for the New Moon!