Any favor you do will be spontaneous and not forced

Philemon 1:12-25
Any favor you do will be spontaneous and not forced.
No longer as a slave, but better than a slave as a dear brother.
I do wish, brother, that  I may have some benefit from you in the Lord; refresh my heart in Christ. Confident of your obedience, I write to you, knowing that you will do even more than I ask.
Grace to you and peace from God our Father and the Lord Jesus Christ.(Beginning)
The grace of the Lord Jesus Christ be with your spirit.(End)
Paul asking Philemon to give Onesimus his freedom and send him back, in part for services Paul rendered to Philemon. Paul uses the conventions of the day: a gift given requires a gift in return. Hence his appeal: Philemon owes his christian life to Paul.
There is added pressure from the fact that this letter is to be read to the church in his house.
But Paul is confident Philemon will comply(執行) and 'set his mind at rest'. Everything is couched(措辭) in terms of praise and encouragement.
Why?
Do any favor should be spontaneous and not forced, so as to serve the Lord in the church.
This letter provides the clearest evidence of how Paul would deal with slavery within the community of Christ. It is not acceptable - and he intends the Christian community to be an example of what the world should be like. Although Paul does not specifically address slavery as an institution, his requirement lays a depth charge beneath it.
The brother in Christ is better than any identity in the world, so do good to our brothers.
How?
Any favor you do will be spontaneous and not forced. With love to do the good things.