From A Man Without A Country (2005):
I am, incidentally, Honorary President of the American Humanist Association, having succeeded the late, great Isaac Asimov in that totally functionless capacity. We had a memorial service for Isaac a few years back, and I spoke and said at one point, “Isaac is up in heaven now.” It was the funniest thing I could have said to an audience of humanists. I rolled them in the aisles. It was several minutes before order could be restored. And if I should die, God forbid, I hope you will say, “Kurt is up in heaven now.” That’s my favorite joke.