“Before borrowing money from a friend, decide which you need more” is a saying that has been cited in print since at least 1961. Addison H. Hallock has been most frequently credited for the saying, but it’s not known when he said this or even who Hallock is. The saying means that one shouldn’t borrow money from a friend because the financial liability could ruin the friendship.
 
     
Google Books
The Saturday Evening Post
Volume 234
1961
Pg. 51:
Before borrowing money from a friend, decide which you need more. ADDISON H. HALLOCK
 
21 March 1961, The Valley News and Valley Green Sheet, “News-Graphs Expressed Editorially” by Walter Mendenhall, pg. 1, col. 1:
OFT-PROVED
Before you borrow money from a friend, decide which you need more.
—Sepulveda - Mission Hills
Kiwanigram
 
Google News Archive
13 April 1961, The Spokesman-Review (Spokane, WA), “Shop with Sue,” pg. 3, col. 8 ad:
Before borrowing money from a friend, decide which you need more.
 
21 June 1961, The Bee (Danville, VA), pg. 6D, col. 1 ad:
King Cole Sez:
Before borrowing money from a friend decided which you need more.
COLE FURNITURE CO.
 
Google News Archive
3 July 1961, Spokane (WA) Daily Chronicle,  “Poor Man’s Plato” by Hal Boyle, pg. 4, col. 4:
Executive signs on the desk of restaurateur Sherman Billingsley: “Before Borrowing Money From a Friend, Decide Which You Need Most.”
 
24 October 1961, The Oregonian (Portland, OR), Entertainment, pg. 5, col. 2:
MONEY COSTS FRIENDS
Quips John Russell, star of Warner Bros.’ “Lawman” television series: ‘Before borrowing money from a friend, decide which you need more.”
 
Google Books
The Reader’s Digest
Volume 81
1962
Pg. 55:
Before borrowing money from a friend, decide which you need more. — Addison H. Hallock
 
Google News Archive
9 June 1964, The Morning Record (Meridan, CT), “Line-O-Types,” pg. 6, col. 2:
Before borrowing money from a friend, make up your mind which you need more.
 
Google Books
Speech Can Change Your Life
By Dorothy Sarnoff
New York, NY: Doubleday
1970
Pg. 284:
Before borrowing money from a friend, decide which you need more. — ADDISON H. HALLOCK
   
Google Books
Words of Wisdom
Compiled and edited by William Safire and Leonard Safir
New York, NY: Simon & Schuster
1989
Pg. 47:
Before you borrow money from a friend, decide which you need more. — Anonymous
 
Google Books
Quotes, Jokes & Anecdotes
By Gerard O’Boyle
Leicestershire: Matador
2012
Pg. 79:
Before borrowing money from a friend decide which you need more.