Woody Allen’s paternity for this quote is unclear. Check Wikiquote under the picture.
This quote is… well, it’s unclear, read below please.
Wikiquote about the quote paternity for Eternity is a very long time
Earliest published reference is a 2007 book which itself cites a 2004 article by someone called “Steiner”, which from the note was a review of a religious book and thus probably not a primary source. The book under review was by someone called “Bouretz” so Steiner’s article is probably “Zion’s Shadows” from the 27 Feb 2004 London Times Literary Supplement, referenced here and here. Hypnosifl 10:29, 12 January 2012 (UTC)
Found an earlier one, the variant “eternity is a long time, especially towards the end” from the 6 January 2001 issue of the British Medical Journal in an article by “Kevin Barraclough, general practitioner”, see snippets here and here. Looks like the article is this one from the bmj.com site. Hypnosifl 10:42, 12 January 2012 (UTC)
An email from Quote Investigator which is quoted here mentions that the earliest citations seem to be in French, and if you google “‘l’éternité”, “long”, and “surtout vers la fin” you do get earlier citations, like this one from 1984 which credits it to Woody Allen, but there are much earlier citations which don’t credit it to Allen, the earliest I found is the 1965 book Le Roi Des Rats by Maurice Frot, which says “il en avait pour l’éternité et c’est long, oui, « surtout vers la fin », disait le Tchèque.” But who knows if Frot originated it or was just quoting someone else.
And the next one after that I find is the 1969 book Le Temps de boules de neige by Pierre Henri Degrégori which says “Je me suis dit in petto : « Mon vieux, si tu ne trouves rien d’original dans les deux secondes qui viennent tu vas être porté absent pour un bout de temps, peut-être pour l’éternité, et l’éternité c’est long, surtout vers la fin. » Mais au bout d’une seconde et demie, elle a appuyé sur la détente.”