Proverbs 18:19

A brother offended is harder to be won than a strong city: and their contentions are like the bars of a castle.

A brother who has been offended is difficult to reconcile and harder to win back than a fortified strong city. The disputes that follow the offense form barriers like the bars of a castle that shut out reunion. Spreading harmful or unverified reports wounds a fellow believer and deepens division, producing the hard-to-remove estrangement that makes reconciliation so difficult.