“The devil makes his Christmas pie of lawyers’ tongues and clerks’ fingers” is often said to be an old English proverb, but it appears to be an Italian proverb. John Florio (Giovanni Florio in Italian) wrote in Second Fruits (1591):
 
“Of three things the deuill makes his messe, Of lawyers tongues, of scriueners fingers, you the third may gesse.”
 
Thomas Adams’ Works (1629), credited the line as an Italian proverb:
 
“Corrupt and consciencelesse lawyers you will confesse to be sharp and wounding brambles. (...) The Italians haue a shrewd prouerbe against them. The Deuill makes his Christmas-pyes of lawyers tongues, and clerkes fingers.”
 
The saying has been cited in print in the United States since at least 1851.
 
   
Google Books
An Exposition of the Several Offices Adapted for Various Occasions of Public Worship
Compile from the works of Rev. John Boys
By Rev. Kensey Johns Stewart
New York, NY: Stanford and Swords
1851
Pg. 655:
Art thou a lawyer? examine thy client’s cause faithfully, turn thy books exactly, prosecute his affairs industriously, lest that Italian proverb be verified, “The devil makes his Christmas pie of lawyers’ tongues and clerks’ fingers.”
   
Google Books
English Proverbs and Proverbial Phrases:
Collected from the Most Authentic Sources (Second Edition)
By W. Carew Hazlitt
London: Reeves and Turner
1882
Pg. 376:
The devil makes his Christmas-pie of lawyers’ tongues and clerks’ fingers.
 
22 December 1889, Cleveland (OH) Plain Dealer, “Old English Christmas Saws,” pg. 4, col. 4:
The devil makes his Christmas pie of lawyers’ tongues and clerks’ fingers.
 
Google Books
Lawyers and Other Reptiles II:
The Appeal
By Jess M. Brallier
Chicago, IL: Contemporary Books
1996
Pg. 29:
The devil makes his Christmas pie of lawyers’ tongues. — English pub toast
 
Google Books
The New Lawyer’s Wit and Wisdom:
Quotations on the Legal Profession, in Brief
By Bruce M. Nash, Allan Zullo and Kathryn Zullo
Philadelphia, PA: Running Press
2001
Pg. 50:
The Devil makes his Christmas pie of lawyers’ tongues.
ENGLISH PROVERB
 
Google Books
The Wordsworth Dictionary of Proverbs
By George Latimer Apperson
Ware, Herts.: Wordsworth Reference
2006
Pg. 141:
The devil makes his Christmas pies of clerks’ fingers and lawyers’ tongues.
1591: Florio. Second Frutes, 179, Of three things the deuill makes his messe, Of lawyers tongues, of scriueners fingers, you the third may gesse.
1630: T. Adams, Works, 145, An euill tongue is meate for the deuill, according to the Italian prouerbe: the deuill makes his Christmasse pie of lewd tongues.
1659: Howell, II, (9).
 
Google Books
The Oxford Dictionary of Phrase and Fable
Edited by Elizabeth Knowles
New York, NY: Oxford University Press
2005, ©2006
Pg. ?:
the Devil makes his Christmas pies of lawyers’ tongues and clerks’ fingers proverbial saying, late 16th century, in which the lawyers’ tongues and clerks’ fingers stand for the words and actions of the legal profession as welcomed by the Devil.
 
Twitter
Legal Tweets
‏@LegalTweeting
The devil makes his Christmas pies of lawyers’ tongues and clerks’ fingers. -THOMAS ADAMS
10:43 AM - 3 Jan 10