Wesley never said that.
This phrase has become a bit of a buzzword in contemporary Methodism and it is almost always connected to John Wesley. Wesley did use the phrase “Christian conference.” And most people who use “holy conferencing” make a connection to “Christian conference.”
In the “Large Minutes” Wesley listed “Christian conference” as one of five instituted means of grace (practices that were instituted by Christ). The instituted means of grace in the “Large Minutes” are: prayer, searching the Scripture, the Lord’s Supper, fasting, and Christian conference.
Here is what is said about Christian conference in this context:
5. Christian Conference.
Are we convinced how important and how difficult it is to order our conversation right?
It is always in grace? Seasoned with salt? Meet to minister grace to the hearers?
Do we not converse too long at a time? Is not an hour at a time commonly enough?
Would it not be well to plan our conversation beforehand? To pray before and after it?
[Bicentennial Edition of the Works of John Wesley, edited by Henry D. Rack, 10:856-7.]
“Christian conference” is often used as a synonym for “holy conferencing,” which seems to mean polite conversation, or being nice when we disagree. But is that what Wesley meant by the phrase? I am writing a post that explores this question, which will be up in a day or two.
For now, there is no evidence that Wesley used the phrase “holy conferencing.” We can add it to the list of things he did not say:
“personal and social holiness” [Original post here.]
“Do all the good you can, by all the means you can, in all the ways you can, in all the places you can, at all the times you can, to all the people you can, as long as ever you can.” [Original post here.]
“I set myself on fire and people come to watch me burn.” [Original post here.]
“In essentials, unity; in non-essentials, liberty; and, in all things, charity.” [Original post here.]