Cover and title of Cerebus #65, August 1984, collected in Church & State I, p. 7 and 273
Usually quoted with "Anything" unspaced (as in the title p. 7), sometimes quoted spaced (as in the art p. 273, as "Any thing done for the first time unleashes a demon.") because the cover art http://www.comics.org/issue/175338/ piles "Any" and "thing" (though they are joined, the leg of the "y" being also the bar of the "t").
Compare to a quote misattributed to Emily Dickinson: "Whenever a thing is done for the first time, it releases a little demon." (origin and date unknown, also attributed to Dave Sim)
Church & State volume I (1987)