Offended brother

An offended brother is harder to win than a city.

A brother offended is harder to be won than a strong city: and their contentions are like the bars of a castle. (Proverbs 18:19 [KJV])

It seems not to be good to offend a brother

King James Bible Mark 9:42
And whosoever shall offend one of these little ones that believe in me, it is better for him that a millstone were hanged about his neck, and he were cast into the sea.

But if you are truly a child of God, you don't get offended.

Great peace have they which love thy law: and nothing shall offend them. (Psalms 119:165 [KJV])