I have to say that's a pretty good sound bite, almost as good as, "Do unto others as you would have them do unto you." A lot of people think Jesus said that, because it is so much the sort of thing Jesus liked to say. But it was actually said by Confucius, a Chinese philosopher, 500 years before there was that greatest and most humane of human beings, named Jesus Christ.(source)
Now thanks to Mr. Vonnegut we have yet another error half-educated people will repeat as Gospel truth. Confucius, in his Analects, actually formulates the negative version of the Golden Rule, "Do not do to others what you would not like yourself." Jesus, of course, says "Do unto others as you would have them do unto you" in Matthew 7:12. The negative version of the rule promotes a live and let die attitude, while the positive version enjoins feeding the hungry, clothing the naked, and more meddlesome deeds like idol-smashing.