The capitalists will sell us the rope with which to hang them.

Commonly attributed to Lenin, but not found in any of his published works.

The Oxford Dictionary of Quotations (5th edition) points out that 'Remembrances of Lenin', by I. U. Annenkov, includes a manuscript note attributed to Lenin: "They [capitalists] will furnish credits which will serve us for the support of the Communist Party in their countries and, by supplying us materials and technical equipment which we lack, will restore our military industry necessary for our future attacks against our suppliers. To put it in other words, they will work on the preparation of their own suicide." [in Novyi Zhurnal/New Review September 1961]

In the book 'They Never Said It', also by Oxford Press, the quote is said to be fake. According to the book, "Lenin was supposed to have made his observation to one of his close associates, Grigori Zinoviev, not long after a meeting of the Politburo in the early 1920s, but there is no evidence that he ever did. Experts on the Soviet Union reject the quote as spurious."