Jamieson, Fausset and Brown on Colossians 4:8

8. for the same purpose--Greek, "for this very purpose."

that he might know your estate--Translate, "that he may know your state": answering to Col 4:7. So one very old manuscript and Vulgate read. But the oldest manuscripts and the old Latin versions, "that YE may know OUR state." However, the latter reading seems likely to have crept in from Ep 6:22. Paul was the more anxious to know the state of the Colossians, on account of the seductions to which they were exposed from false teachers; owing to which he had "great conflict for" them (Col 2:1).

comfort your hearts--distressed as ye are by my imprisonment, as well as by your own trials.