Whoever restrains her (the contentious) restrains the wind, and grasps oil with his right hand. (Proverbs 27:15-16)
The strong connotation here is that the contentious cannot be restrained. It is nearly foolish to attempt to do so.
Therefore how do we deal the contentious? There are several simple ways: one of my favorite ways is not to deal with them at all. I prefer to leave them to their own devices. If I have a relationship with them, I reveal their attitudes to them firmly in love and depart from them. Always remember, the contentious want to be contentious. Do not feed them their fodder. Like all antagonists, we are to love them, but mark them. They do not make for godly friends or associates.
If you happen to have authority in their lives, discipline them. And if the discipline fails, you may have to remove yourself from them or remove them from you, especially if they are employed by you. If they happen to be a spouse, pray for them, love them and minister to them even though it will be like grasping oil in your hand.