Proverbs 18:19 (BSB)

An offended brother is harder to win than a fortified city, and disputes are like the bars of a castle.

From Proverbs 18. Also in the ESV.

Commentary on Proverbs 18:19

• Matthew Henry (Presbyterian), Matthew Henry's Complete Commentary on Proverbs 18:19: Note, 1. Great care must be taken to prevent quarrels among relations, and those that are under special obligation to each other, not only because they are most unnatural and unbecoming, but because between such things are commonly taken most unkindly, and resentments are apt to be carried too far.
• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Proverbs 18:19: A brother offended is harder to be won than a strong city,.... A fortified city may sooner be taken by an enemy, than one brother offended can be reconciled to another; their resentments against each other are keener than against another person that has offended them; and their love being turned into hatred, it is more bitter; and it is more difficult to compose differences...
• Jamieson-Fausset-Brown (Reformed), Commentary Critical and Explanatory on the Whole Bible on Proverbs 18:19: No feuds so difficult of adjustment as those of relatives; hence great care should be used to avoid them.
• Geneva Bible Notes (Reformed), Geneva Bible Study Notes on 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. (n) Which for the strength of it will not bow or yield.