Bere Folkner

“Never assume that the person you are dealing with is weaker or less important than you are. Some people are slow to take offense, which may make you misjudge the thickness of their skin, and fail to worry about insulting them. But should you offend their honor and their pride, they will overwhelm you with a violence that seems sudden and extreme given their slowness to anger. If you want to turn people down, it is best to do so politely and respectfully, even if you feel their request is impudent or their offer ridiculous.”
― Robert Greene, The 48 Laws of Power