1 Thessalonians 3:11-12

And to make it your ambition to live quietly and peacefully, and to mind your own affairs and work with your hands, just as we directed you, so that you will behave properly toward outsiders (exhibiting good character, personal integrity, and moral conduct worthy of respect of the outside world), and be dependent on no one and in need of nothing.  

The only person we can control in our lives is ourselves; minding other people’s business leads to frustration. Who knows, we may have the right opinion about a person, but it may be the wrong opinion about that person, too. It is best to keep our focus on God and our own affairs and develop our characters in case we are the ones lacking.