In a scene in Lao She's drama Teahouse, there is a banner saying "Don't talk about state affairs" in the teahouse.

As early as in the biography of Nan Shi Xu Mian, "We can only talk about romantic affairs in the past and present, but not about business." Hint not to talk about state affairs.

Also, don't say country, yes has the same meaning as "yes" in "* * * commerce"