“Were it not that they are loath to lay out money on a rope, they would be hanged forthwith, and sometimes die to save charges.”

A variant of the above misquote, sometimes also attributed to Lenin. This gained popularity during the glasnost era when black market activity was at its most visible in the USSR; meant to show the profit motive was human nature and cannot be eradicated.
Misattributed

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

Variant: Your money saved us for three days. It's not often that money saves a person's life.
Source: The Alchemist (1988), p. 167 <!-- p. 148 -->

Source: Zombies Vs. Unicorns

Introductio ad prudentiam: Part II (1727), Gnomologia (1732)

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.