“It is wise to listen, not to me but to the Word, and to confess that all things are one.”
Fragment 50, as translated in the Loeb Classics edition http://www.loebclassics.com/view/heracleitus_philospher-universe/1931/pb_LCL150.471.xml?rskey=IyhfrN&result=8
Variant translations:
Listening not to me but to reason, it is wise to agree that all is one.
Listening not to me but to the Word it is wise to agree that all things are one.
He who hears not me but the logos will say: All is one.
It is wise to hearken, not to me, but to my Word, and to confess that all things are one.
The word translated in these quotes and many others as "The Word" or "Reason", is the greek word λόγος (Logos).
Numbered fragments
Original
οὐκ ἐμοῦ, ἀλλὰ τοῦ λόγου ἀκούσαντας ὁμολογεῖν σοφόν ἐστιν ἓν πάντα εἶναί
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Heraclitus 46
pre-Socratic Greek philosopher -535Related quotes

“Society speaks and all men listen, mountains speak and wise men listen.”
Frequently attributed to Muir without source. An extensive search of Muir's published and unpublished writings found several sharp and cogent observations concerning society (see above) but not this one.
Misattributed
“When you seem to be listening to my words, they are your words, with me listening.”
Cuando me parece que escuchas mis palabras, me parecen tuyas mis palabres y escucho mis palabras.
Voces (1943)

About King Charles II of England, as quoted in Blackwood's Edinburgh Magazine Vol. XLIV (January - June 1857) p. 592; It is said to that this was written on the door of Charles II’s bedchamber, and that on seeing it, the king replied, “This is very true: for my words are my own, and my actions are my ministers’....”
Other

“A word to the wise ain't necessary, it's the stupid ones who need advice.”

Written on the Bedchamber Door of Charles II, as quoted in The Book of Days : A Miscellany of Popular Antiquities (1832) by Robert Chambers, Viol. II, July 26, p. 126.