When people entertain others without an introduction they generally turn out more like devils than angels.
 Samuel Butler, The Note-Books of Samuel Butler (1912). copy citation

Context

“but then he sent for me through mutual friends in the usual way. Entertaining Angels I doubt whether any angel would find me very entertaining. As for myself, if ever I do entertain one it will have to be unawares. When people entertain others without an introduction they generally turn out more like devils than angels. Myself and My Books The balance against them is now over £350. How completely they must have been squashed unless I had had a little money of my own. Is it not likely that many a better writer than I am is squashed through want of money?” source