“Beware of bugs in the above code; I have only proved it correct, not tried it.”
Donald Knuth's webpage http://www-cs-faculty.stanford.edu/~knuth/faq.html states the line was used to end a memo entitled Notes on the van Emde Boas construction of priority deques: An instructive use of recursion (1977)
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Donald Ervin Knuth 32
American computer scientist 1938Related quotes

How Did Software Get So Reliable Without Proof? Lecture Notes in Computer Science vol 1051 1996 pp. 1-17 : FME '96: Industrial Benefit and Advances in Formal Methods, Third International Symposium of Formal Methods Europe, Co-Sponsored by IFIP WG 14.3, Oxford, UK, March 18-22, 1996, Proceedings.

And I said, "Well that's wrong."
A Conversation with Ward Cunningham (2003), Collective Ownership of Code and Text
“No moral code is right, correct, true. That's nihilism. And we have to accept it.”
The Atheist's Guide to Reality (2011)
Context: Scientism starts with the idea that the physical facts fix all the facts, including the biological ones. These in turn have to fix the human facts—the facts about us, our psychology, and our morality. After all, we are biological creatures, the result of a biological process that Darwin discovered but that the physical facts ordained. As we have just seen, the biological facts can't guarantee that our core morality (or any other one, for that matter) is the right, true, or correct one. If the biological facts can't do it, then nothing can. No moral code is right, correct, true. That's nihilism. And we have to accept it.
M. B. Douthwaite (2002) Enabling Innovation: A Practical Guide to Understanding and Fostering Technological Change. p. 116

Source: Are you being brainwashed?: Propaganda in science textbooks (2007), p. 24

Jokes and their Relation to the Cognitive Unconscious (1980)
NANOG mailing list http://www.merit.edu/mail.archives/nanog/2002-02/msg00482.html (2002)
Notes: talking about software security bugs.