Now often abbreviated to a word to the wise. Cf. L. verbum sat sapienti, a word is sufficient to a wise man; also verb. sap.
Few wordis may serve the wyis.
[a 1513 Dunbar Poems (1979) 206]
Fewe woords to the wise suffice to be spoken.
[1546 J. Heywood Dialogue of Proverbs ii. vii. 14V]
They say, a word to the Wise is enough: so by this little French that he speakes, I see he is the very man I seeke for.
[a 1605 W. Haughton Englishmen for my Money (1616) D3]
A word, Mons. Yorick, to the wise‥is enough.
[1768 Sterne Sentimental Journey III. 164]
‘Fred!’ cried Mr. Swiveller, tapping his nose, ‘a word to the wise is sufficient for them—we may be good and happy without riches, Fred.’
[1841 Dickens Old Curiosity Shop ii.]
The Man With the Proverbial Word to the Wise.
[2002 Washington Times 25 Apr. C10 (heading)]
Related to: hints
Bibliography of major proverb collections and works cited from modern editions is available here.
Here's good advice, as in A word to the wise: don't walk alone here because these streets are not safe at night. A shortening of A word to the wise is enough, as it was put by Roman writers, this phrase in English dates from the mid-1500s.