2 Corinthians 8:6

Insomuch that we exhorted Titus, that as he had made a beginning before, so he would also complete in you this grace also.

We are heartily in agreement with Tasker who said:

This visit would seem to have taken place about a year before (2 Corinthians 9:2); and it may be a legitimate inference that Titus himself was the bearer of 1Corinthians in which Paul's instructions on this subject were given (1 Corinthians 16:1ff).[14]

The grace also ... That Paul's words here may be touched with a bit of friendly irony may not be ruled out. Certainly, some of the first epistle is loaded with outright sarcasm; and, in a church of so many pretensions to "knowledge," and with Paul's immediate reference to their abounding in "knowledge," there would seem to be here a very delicate suggestion that perhaps the deeds of the Corinthians ought to catch up with their "knowledge."