У страха глаза велики (u strákha glazá velikí).

Literally: fear has big eyes.

Explanation: people who are afraid of something often overestimate the danger or tend to see the danger everywhere.

English equivalents:

• fear takes molehills for mountains;
• fear hath a hundred eyes;
• fear has many eyes.

P.S. All stills are taken from the classic Soviet horror film “Viy” (Mosfilm, 1967) based on the Nikolai Gogol story.