you can never be too careful; better safe than sorry
A proverb meaning that one should always be cautious and assume the worst to avoid danger. Literally: 'When you see fire, think it's a fire.'
As the saying goes, 'When you see fire, think it's a fire' — it's best to act immediately if you sense anything unusual.
A traditional Japanese proverb. The exact origin is uncertain, but it reflects a common-sense warning to treat any sign of danger seriously.