Alexander Campbell's Favorite Joke?

Okay, here's a question for any Stone-Campbell historians out there: Did Alexander Campbell have a favorite joke?

I've heard that he did. If so, I'd like to track it down (that is, if it's to be found among his writings). At this point, all I have is oral tradition. Here's what I recall from what I was told:

Like a lot of brainy, industrious people, Campbell had a lively sense of humor. But like a lot of funny people, he didn't tell many jokes. Instead, he would quip about this, comment on that, often in a way that made people smile. However, there was one joke he liked to repeat. It went something like this:

Once there was a young preacher who was traveling to another city by coach. A few minutes after he boarded, he was joined by two older attorneys, members of a firm which was known for getting its rich, guilty clients off the hook.

Soon after the trip began, one of the lawyers exchanged introductions with the young preacher and asked him, "And what do you do for a living?"

"I'm a preacher of the gospel of Jesus Christ," he said.

Hearing that, the two crusty old men looked at each other as if to say, "Let's have a little fun with this youngster." So one of them started in, doing what lawyers do. Asking questions.

"I've sometimes wondered this about preachers: In the midst of a sermon, do you ever say something that you didn't mean to say? Something erroneous?"

"Yes," said the preacher, "I'd say that happens sometimes."

"Well, in that case, once you realize it was an error, do you go back and correct it?"

"That depends," said the preacher.

"Depends? Depends on what?"

"Well, if it was a serious error of fact, something that makes a real difference, then I go back and correct it. But if the difference is negligible, then I just go on."

"Sounds like a good principle," said the lawyer. "But could you give an example of how you would use it?"

"Alright. Let's say that I went to quote the passage from the Book of Revelation that says, 'All liars shall have their place in the lake of fire.' but instead it came out, 'All lawyers shall have their place in the lake of fire'."

"Well, what would you do?" asked the lawyer, his eyebrows raised high.

"I'd consider that such a slight difference, I'd just go on."

Supposedly, this was Campbell's favorite, oft-repeated joke. Can anyone verify? Cite a source?