Musar על שבת 299:6

The details of these laws according to their differences are explained by the Halachic deciders (Poskim) in their books. All of these details are equal for all us with respect to their obligation and requisite watchfulness. That which is difficult on the masses to guard is abstaining from business occupation and conversation. This prohibition is stated in the words of the prophet (Isaiah 58:13): "if you honor it, abstaining from your own ways, not pursuing your affairs and speaking words about them". The general principle is that whatever is forbidden to do on the Sabbath is forbidden to strive after or mention verbally.