"He who passes by & meddles in a quarrel not his own is like one who takes a dog by the ears." Proverbs 26:17
Not much to add to this verse. Usually 'mind your own business' comes to mind. Not that we shouldn't help or intervene when necessary, but this is reminding us that we don't need to get in the middle of 'other people's business' because the outcome is usually not good.