Paul wrote a letter to Philemon to ask him a favor. Today we find his letter in the New Testament. Philemon had a slave called, Onesimus but he had stolen from Philemon and ran away to Rome. Once in Rome he rather surprisingly met Paul and became a Christian. Paul wanted him to stay in Rome with him so Onesimus could help provide for his needs while he was in prison. However Paul sent him back to Philemon with his letter.
Paul already knew Philemon since he was a Christian at the church in Colosse. Paul wrote, "I would have liked to keep him with me so that he could take your place in helping me. But I did not want to do anything without your consent, so that any favor you do will be spontaneous and not forced" (Philemon 13-14).
Paul could have kept Onesimus with him which would have made Paul's life a bit easier but he didn't want to presume upon Philemon's kindness. Even though it seems clear that Philemon would have been happy to help in any way he could ("knowing that you will do even more that I ask" v.21). Nevertheless Paul didn't want to force Philemon into giving him help.
We do others a disservice when we presume upon their kindness or put them under some sort of obligation to assist even if it is for the cause of the gospel. We may see a great opportunity to advance the kingdom but we mustn't press others into in doing us a kindness without their freely given consent. It is God who convicts, challenges and guides His children, not us. If we coerce others into serving they lose the reward that could be theirs because they are not serving with a willing heart.
God wants our service to be freely given from a heart of thankfulness, not from a sense of obligation.