Akademik

Не зная дела, не суди
If you are incompetent in some matter, do not give your opinion on it. See Слепой курице все пшеница (C)
Cf:
A blind man is no judge of colors (Am.). A blind man should not judge colo(u)rs (Am., Br.)

Русско-английский словарь пословиц и поговорок. . 2013.