“1657. Give him but Rope enough, and he'll hang himself.”

The Clerk's Vision (1949)
Context: The world stretches out before me, the vast world of the big, the little, and the medium. Universe of kings and presidents and jailors, of mandarins and pariahs and liberators and liberated, of judges and witnesses and the condemned: stars of the first, second, third and nth magnitudes, planets, comets, bodies errant and eccentric or routine and domesticated by the laws of gravity, the subtle laws of falling, all keeping step, all turning slowly or rapidly around a void. Where they claim the central sun lies, the solar being, the hot beam made out of every human gaze, there is nothing but a hole and less than a hole: the eye of a dead fish, the giddy cavity of the eye that falls into itself and looks at itself without seeing. There is nothing with which to fill the hollow center of the whirlwind. The springs are smashed, the foundations collapsed, the visible or invisible bonds that joined one star to another, one body to another, one man to another, are nothing but a tangle of wires and thorns, a jungle of claws and teeth that twist us and chew us and spit us out and chew us again. No one hangs himself by the rope of a physical law. The equations fall tirelessly into themselves.
And in regard to the present matter, if the present matters: I do not belong to the masters. I don't wash my hands of it, but I am not a judge, nor a witness for the prosecution, nor an executioner. I do not torture, interrogate, or suffer interrogation. I do not loudly plead for leniency, nor wish to save myself or anyone else. And for all that I don't do and for all that they do to us, I neither ask forgiveness nor forgive. Their piety is as abject as their justice. Am I innocent? I'm guilty. Am I guilty? I'm innocent. (I'm innocent when I'm guilty, guilty when I'm innocent. I'm guilty when … but that is another song. Another song? It's all the same song.) Guilty innocent, innocent guilty, the fact is I quit.

Source: The Name of the Wind (2007), Chapter 39, “Enough Rope” (p. 281)

Posthumous attributions, Tupac: Resurrection (2003)
Source: Resurrection, 1971-1996

According to the book, "They Never Said It", p. 64, there is no evidence Lenin ever said this. 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 rope quote as spurious.
Misattributed

Often attributed to Stalin and Marx, according to the book, They Never Said It (1989), p. 64, the phrase derives from a rumour that Lenin said this 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. It has also been believed that Lenin may have expressed that the profit motive cannot be undone in that "If we were to hang the last capitalist, another would suddenly appear to sell us the rope". Experts on the Soviet Union reject the rope quote as spurious. However, it is established that Lenin did remark on the same underlying theme (even if not in reference to rope), namely, that capitalists in their addiction to high profits could not help themselves from selling things to a socialist state, even if it was against their own long-term interests by strengthening an enemy; Edvard Radzinsky covers it in his discussion of Lenin's comments on the "deaf-mutes" in Radzinsky's biography of Stalin.
Misattributed

Often attributed to Lenin or Stalin, less often to Marx. According to the book, "They Never Said It", p. 64, the phrase derives from a rumour that Lenin said this 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 rope quote as spurious.
Misattributed

The earliest citation yet found does not attribute this to Roosevelt, but presents it as a piece of anonymous piece folk-wisdom: "When one reaches the end of his rope, he should tie a knot in it and hang on" ( LIFE magazine (3 April 1919), p. 585 http://hdl.handle.net/2027/wu.89063018576?urlappend=%3Bseq=65).
Misattributed
Variant: When you come to the end of your rope, tie a knot and hang on.