Entry in progress—B.P.
 
“Speak the truth, even if your voice shakes” is a similar saying.
 
The Yale Book of Quotations
Edited by Fred R. Shapiro
New Haven, CT: Yale University Press
2006
Pg. 21:
“Speak Truth to Power.”
Title of pamphlet by American Friends Service Committee (1955). Bayard Rustin, one of the pamphlet’s authors, had written in a 15 Aug. 1942 letter: “The primary function of a religious society is to speak the truth to power.”
     
Wikipedia: Benjamin Haydon
Benjamin Robert Haydon (26 January 1786 – 22 June 1846) was an English historical painter and writer.
(...)
Haydon was well known as a lecturer on painting and design, and from 1835 onwards visited all the principal towns in England and Scotland on lecture tours. His ambition was to see the chief buildings of Britain adorned with history paintings representing her glory. He lived to see the establishment of schools of design, and the embellishment of the new Houses of Parliament; but in the competition of artists for the carrying out of this object, the commissioners (including one of his former pupils) considered that he had failed. Haydon’s Lectures, which were published shortly after their delivery, showed that he was as bold a writer as painter. It may be mentioned in this connection that he was the author of the long and elaborate article, “Painting,” in the 7th edition of the Encyclopædia Britannica.
 
Google Books
Lectures on Painting and Design
vol. 2
By Benjamin Robert Haydon
London: Brown, Green, and Longmans
1844-46
Pg. 221:
...a paltry apprehension of the consequences of telling truth to power or to learning, had made him cow under the frown of their offended pride?
   
Google Books
Marble Isle:
Legends of the round table, and other poems
By Sallie Bridges
Philadelphia, PA: J. B. Lippincott
1864
Pg. 179:
Drink, gallant knights, to the minstrel
Who dreads neither prince nor peer, —
Who can speak the truth to power,
Nor flatters for price or fear,...
 
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October 1876, Harper’s New Monthly Magazine, “Haydon and His Friends,” pg. 651, col. 2:
He also wrote an epitaph which he wished inscribed on his tombstone when the time came. It embodies his own estimate of his career:
 
“Here lieth the body of BENJAMIN ROBERT HAYDON, an English Historical Painter, who, in a struggle to make the People, the legislature, the Nobility, and the Sovereign of England give due dignity and rank to the highest Art, which had ever languished, and until the Government interferes will ever languish in England, fell a victim to his ardor and his love of country; an evidence that to seek the benefit of your Country, by telling the truth to Power, is a crime that can only be expiated by the ruin and destruction of the man who is so patriotic and imprudent. he died believing in Christ as the Mediator and Advocate of Mankind.
   
Google Books
Correspondence and table-talk; with a memoir
By Benjamin Robert Haydon and Frederic Wordsworth Haydon
London: Chatto & Windus
1876
Pg. 334:
To tell the truth to power is an everlasting crime, which time never effaces and mankind never forgives. To lessen any man in his own conviction, or in the conviction of others, is too severe a test for self-respect.
       
Google Books
July 1877, The Galaxy, pg. 11, col. 2:
For in England, as here, the voice of the majority is a power in literary judgments, or in political and social, that is perhaps too little checked by right reason, and “telling the truth to power,” as Haydon said, speaking from experience, “is a crime that can only be expiated by the ruin and destruction of the man who is so patriotic and so independent.”
 
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The early life, correspondence and writings of the Rt. Hon. Edmund Burke, LL. D., with a transcript of the minute book of the debating “Club” founded by him in the Trinity College, Dublin.
By Edmund Burke; Arthur Purefoy Irwin Samuels; Arthur Warren Samuels; Trinity College (Dublin, Ireland). Academy of Belles Lettres
Cambridge University Press
1923  
Pg. 341:
Strange it is that men should be found abject enough to tremble at the very thought of speaking truth to power! Even to unauthorized power!
 
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The National Character
By Arthur Bryant
London: Longmans, Green and Company
1934
Pg. 52:
...to the evils of sweated woman and child labour, speaking, in Mr. and Mrs. Hammond’s fine words : ” truth to power in its selfishness and sloth.”
       
Google Books
Lord Shaftesbury
4th edition
By Barbara Bradby Hammond
London: Longmans, Green
1936
Pg. 276:
This was his service to England; not the service of a statesman with wide plan and commanding will, but the service of a prophet speaking truth to power in ...
   
Google Books
The life and death of Benjamin Robert Haydon, 1786-1846
By Eric George
London: Oxford University Press
1948
Pg. 5:
It was his unfortunate habit to ‘tell the truth to power’, as he expressed it.
Pg. 309:
He was a good Father, a faithful & tender Husband, and lived an indisputable evidence, if any was wanting, that no affliction is considered an adequate punishment for having told Truth to Power.
   
OCLC WorldCat record
Speak truth to power : a Quaker search for an alternative to violence : a study of international conflict.
Author: American Friends Service Committee.
Publisher: Philadelphia, Pa. : American Friends Service Committee, 1955.
Edition/Format: Book : English