@cicerone imposter,
http://forum.quoteland.com/eve/forums/a/tpc/f/99191541/m/485100021
I found a few other occurrences:
A proverb attributed to Thomas Becon (1560).
The dead can tell no tales~John Wilson, Andronicus Commenius, Act I, sc. 4 (1664).
First appeared in the U.S. in Porcupine's Works (1797).
It may have occurred earlier in another form.
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Will Durant's Age of Faith volume 4, in his Civilization series quotes p 530 of Lewis Browne's "Wisdom of Israel," NY, 1945, as attributing this line to the medieval Persian poet Sa'di, around 1250, saying this is what we should to to all quacks and charlatans:
"So I finished the rogue, notwithstanding his wails,
With stones, for dead men, as you know, tell no tales."