When thy neighbour's house is on fire, be careful of thine own.

Another person's disaster, whether a literal nearby fire or a metaphor for a closely related danger, may expose a risk that could soon reach you. Their misfortune should prompt alertness and practical steps to protect what is vulnerable in your own affairs.

The saying recommends prudence rather than indifference. A crisis nearby can warn you to examine your own preparations, because similar causes or consequences may affect more than one household.

Use it when a problem affecting someone nearby—literal, financial, social, or organizational—should lead others to assess comparable risks. Its archaic possessives give it a proverbial, formal tone; a modern paraphrase may suit ordinary conversation.