9 And you, masters, do the same things to them, giving up threatening, knowing that your own Master also is in heaven, and there is no partiality with Him.
There were two sides to the master-slave relationship. The slave had mandates from God and so did the master. God did not leave the master unchallenged.
And you, masters,
Masters were to treat their slaves the same way as slaves served their masters to please the Lord. Slaves were to do their service as to the Lord, and the master was to treat his slaves as to the Lord.
do the same things to them,
Masters were to show the same respect to God’s will as slaves did to their masters. If an employer wants the best from his employees, he should give his best to them.
giving up [forbearing] threatening,
The master was to use his authority in a way that did not operate in a threatening manner. Roman masters had the legal right to kill their slaves. The Christian owner was to treat his slaves with respect. He was not abusive with his authority, nor did he operate on threats to his slaves. Using abusive language is not good leadership.
knowing that your own Master also is in heaven,
The slave owner had a Master in heaven and He is sovereign over everything, not just some plot of ground on earth. The human master stood on the same ground as the slave, with a Master in heaven. There is equality of master and slave in this. The master must practice the lordship of Christ.
and there is no partiality with Him.
There is no partiality with the Master in heaven (Co 4:1; Jas 5:4). God gave no special deference to the master over the slave. The Christian master was to know that he was a fellow slave of Jesus Christ. If he knew this, then he would not play favorites.
Equality of faith is superior to social status among men.
God makes all believers brothers. He plays no favorites and has no favorites. Masters were to treat their slaves with dignity.
The Bible does not condemn nor does it condone slavery. It approaches slavery from how people function within it. This is a transformation of slavery from within, by regenerating people.