It has often been suggested that the reason for Paul dictating his letters was an eye problem making it difficult for him to see. But his blindness was healed when Ananias laid hands on him. I think it is more likely that Paul dictated letters because his arms were chained.
One translation of partner gives comrade in arms. That speaks to me of soldiers in an army. In this case The Army of The Lord. The Greek word used for partner in this verse is koinonia. It is often used in the Christian community about working together and sharing everything.
We get the impression that Onesimus had served Paul during a reasonable period of time. The life change that Jesus had obviously brought about in this former slave is a message to all who read this short epistle. That giving your life to Jesus can bring about huge changes.
This verse makes me think of my childhood and youth. I remember people giving me a choice which went like this:- You can have whichever you like, but take this one! Or something similar. Paul asks Philemon for a favour, and says it is your choice, but please do this!!
At the beginning of these verses we see a description of this new convert; his very heart. Onesimus must have used his experience as a slave to serve Paul in any way he could. Paul was blessed and impressed and was trying to persuade Philemon to accept the new Onesimus.
Up to now Philemon has been personal compliments and encouragements. Here we read the reason Paul is writing to Philemon. In the original Greek, it reads as a play on words. The name Onesimus means useful or profitable. Paul is obviously hoping that his words will make the reader smile.
Paul was imprisoned in Rome under Roman authorities. But he did not consider that to be the reality of his situation. Paul was confident that Jesus was with him in any and every situation, and he made the most of them all. That is a challenge for many believers today.
This letter gives us a glimpse of the changes which are still ongoing in Paul. We see the old Paul, known for his aggression and religiosity, certainly not for his love! The new Paul is encouraging Philemon to take Onesimus back into his employ. We are all on the road.
In the first century, slavery was very much a part of life. A reality throughout the Roman world. Many were well treated, but others were not. Runaway slaves could face severe punishment and even death. So for Onesimus, (the runaway slave turned Christian), it was a life and death situation.
There seems to be a formula in this prayers for Philemon. Yesterday we saw that Paul thought of Philemon with gratitude. Today we see that he is praying for a deepening of understanding of what being a Christian means. Here Paul is praying for that witnessing to change Philemon himself.