American poet Oliver Wendell Holmes, Sr. (1809=1894) wrote in The Poet at the Breakfast-Table (1872):
 
“It is the province of knowledge to speak, and it is the privilege of wisdom to listen.”
 
American rock guitarist Jimi Hendrix (1942-1970) has been credited since 2000 for the quotation:
 
“Knowledge speaks, but wisdom listens.”
 
It’s not known if Jimi Hendrix ever said this—the credit is 30 years after his death—but the quotation appears to be a paraphrase of what Holmes wrote. The supposed Hendrix quote has been printed on many posters, often with the name and image of Hendrix.
 
   
Wikipedia: Oliver Wendell Holmes, Sr.
Oliver Wendell Holmes, Sr. (August 29, 1809 – October 7, 1894) was an American physician, poet, professor, lecturer, and author based in Boston. A member of the Fireside Poets, his peers acclaimed him as one of the best writers of the day. His most famous prose works are the “Breakfast-Table” series, which began with The Autocrat of the Breakfast-Table (1858). He was also an important medical reformer.
 
The Contrary Opinion—Buttons
Knowledge Speaks, But Wisdom Listens
Amazingly, this quotation is widely attributed to Jimi Hendrix (1942-1970) ... but there is no actual proof that he either said it or wrote it. There is, however, proof that Oliver Wendell Holmes (1809-1894) wrote, “It is the province of knowledge to speak, and it is the privilege of wisdom to listen.”
 
Google Books
October 1872, The Atlantic Monthly, “The Poet at the Breakfast-Table” (Chapter X) by Oliver Wendell Holmes, pg. 427:
It is the province of knowledge to speak, and it is the privilege of wisdom to listen.
 
Google Books
The Poet at the Breakfast-Table
By Oliver Wendell Holmes
Boston, MA: James R. Osgood and Company
1872
Pg. 310:
A wise man recognizes the convenience of a general statement, but he bows to the authority of a particular fact. He who would bound the possibilities of human knowledge by the limitations of present acquirements would take the dimensions of the infant in ordering the habiliments of the adult. It is the province of knowledge to speak, and it is the privilege of wisdom to listen.
 
3 June 1924, Richmond (VA)

Times-Dispatch, “Pointed Paragraphs,” pg. 6, col. 5:
It is the province of knowledge to speak, and it is the privilege of wisdom to listen.
     
Google Books
Baby, You Are So Fine:
What Women Need—What Men Want
By Dennis Leonard
Denver, CO: Dennis Leonard Pub.
2000
Pg. X:
Also, he (Bishop Leonard—ed.) has mastered the art of listening. “Knowledge speaks and wisdom listens.”
 
9 June 2000, The Chronicle-Telegram (Elyria, OH), “The 411,” pg. B12, col. 1:
Say what
“Knowledge speaks, but wisdom listens.”
—Jimi Hendrix
 
11 July 2000, Aberdeen (SD) American News, pg. 4 masthead:
“Knowledge speaks, but wisdom listens.”
Jimi Hendrix
 
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“Knowledge speaks, but wisdom listens.” - Jimi Hendrix
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10:02 AM - 9 Dec 2015