This verse does not mean that masters must obey their slaves. It signifies that they must treat their slaves with the same respect that they expect from them. They must treat them justly and fairly (Colossians 4:1). Where pagans threatened their slaves, controlling them through fear,1 Christian masters must not do so. Instead, they are to deal kindly with them because they too have a Master in heaven to whom they will give account and they serve the same Lord as their (Christian) slaves.2
9 Masters, do the same to them, and stop your threatening, knowing that he who is both their Master and yours is in heaven, and that there is no partiality with him.