The apostle Paul had several advises Philemon just like he did for Timothy and Titus. Paul's advise is a good lesson on forgiveness;
"I appeal to you to show kindness to my child, Onesimus. I became his father in the faith while here in prison."
Philemon 1:10 NLT.
Onesimus had offended his master and possibly taken advantage of his kindness and ran away from home. That could have filled Philemon with bitterness at being taken advantage of. And so Paul was asking him to forgive.
Having confirmed Onesimus genuine conversion, Paul sent him back to Philemon to restitute.
The challenge to accept Onesimus back reflects the burden to forgive when we have to.
