Akademik

Глупа та птица, которой гнездо свое не мило
One should not speak bad of the people he lives or works with
Cf: It is a foolish bird that defiles (fouls) its own nest (Br.). It is an ill bird that fouls its own nest (Am., Br.). It's a poor bird that will dirty its own nest (Am.)

Русско-английский словарь пословиц и поговорок. . 2013.