Epistle to Philemon
| Light iron-age reading|
|Gabbin' with God|
Paul is apparently planning a jailbreak, because he asks Philemon, leader of the Colossian church to prepare a lodging for him, in the hope that through their "prayers" (or perhaps a get out of jail free card) he might be restored to them.
Paul also pleads on behalf of Onesimus, a former slave of Philemon whom Paul converted in prison. Paul is sending Onesimus back to them, and please don't make him a slave again. This part of Philemon was later cited by the abolitionism movement in support of ending slavery in the United States, which just goes how sparse Biblical condemnations of slavery are.
There is another later letter attributed to Paul written to the Christians of Colossae, but it's probably not actually by Paul, or at any rate written for him: Colossians.