“As you slide down the ban(n)ister of life, may the splinters never point the wrong way” is a jocular one-line saying that has been printed on many images. “A toast to the bride and groom, ‘As you slide down the banister of life may you never strike a splinter’” was printed in the Norwich (KS) Herald on July 23, 1915.
   
“As you slide down the banister of life, may the splinters never face you the wrong way” became known as an Irish blessing or toast by at least 1981.
   
       
23 July 1915, Norwich (KS) Herald, pg. 4, col. 2:
A toast to the bride and groom, “As you slide down the banister of life may you never strike a splinter.”
 
7 July 1940, Miami (FL)

, pg. 4-C, col. 8:
Autograph, Sayings
As you slide down the banister of life,
May you miss all the splinters.
—Sent by Katherine Driscoll, 10.
 
24 April 1959, Los Angeles (CA) Tribune, pg. 22, col. 2:
CATCH ON?
As you slide down the banister of life, may the splinters never point the wrong way.
 
11 October 1959, The Enquirer (Cincinnati, OH), “Innocent Bystander” by Ollie M. James, pg. 2-F, col. 6:
BUSINESS CARD: “As you slide down the banister of life, may the splinters never point the wrong way.”
 
20 February 1961, The News and Courier (Charleston, SC), “Doing the Charleston” by Ashley Cooper, pg. 6-A, col. 7:
As you slide down the bannister of life, may the splinters never be turned the wrong way.”
 
Google Books
Toasts, the complete book of the best toasts, sentiments, blessings, curses, and graces
By Paul Dickson
New York, NY: Delacorte Press
1981
Pg. 172:
As you slide down the bannister of life May the splinters never face the wrong way.
 
19 March 1981, The Sun, “St. Patty’s Day bar-hopping: The beer is always greener ...” by Robert Fuggetta, [g. AS7, cols. 3-4:
“As you slide down the banister of life, may the splinters never face you the wrong way.”
   
Google Books
14,000 Quips & Quotes:
For Speakers, Writers, Editors, Preachers, and Teachers
By E. C. McKenzie
Grand Rapids, MI: Baker Book House
1990, ©1980
Pg. 303:
As you slide down the banister of life, may the splinters never point your way.
 
Google Books
Irish Wit and Wisdom
By Joan Larson Kelly
White Plains, NY: Peter Pauper Press, Inc.
1998
Pg. 63:
As you slide down the banister of life May the splinters never face the wrong way!
 
13 March 1998, The Gazette (Colorado Springs, CO), “Everything You Wanted To Know About Being Irish*/ *BUT WERE AFRAID TO ASK,” pg. G)20:
“As you slide down the bannister of life, may the splinters never point the wrong way.”
   
24 March 2000, Sarasota (FL) Herald Tribune, “It was a great day for the Irish” by Ann Standerson, pg. 5B:
The big “Polish leprechaun” ended the evening with an “Irish Blessing.” “As you slide down the banister of life, may the splinters never point in the wrong direction.” Aye.
 
Twitter
Cease1‏
@TheCease1
As you slide down the banister of life…you are bound to get a splinter in your rear every now and then.
6:56 PM - 17 May 2008
 
Twitter
Tien N. Nguyen‏
@quotecollection
As you slide down the banister of life, May the splinters never point the wrong way. -Irish Proverb-
12:18 PM - 9 Jun 2008
 
Twitter
snarfoogle‏
@snarfoogle
As you slide down the bannister of life, may the splinters never point your way.
5:59 PM - 2 Sep 2008
 
Twitter
Karen Lewis‏
@simplyamusing
greatest spam line I’ve ever gotten: “As you slide down the bannister of life, may the splinters never point your way”
5:03 PM - 1 Dec 2008
 
Google Books
Over P. J. Clarke’s Bar:
Tales from New York City’s Famous Saloon
By Helen Marie Clarke
New York, NY: Skyhorse Publishing
2012
Pg. 171:
If we could hear him, he might offer this Irish blessing: “As you slide down the banister of life, may the splinters not be pointing the wrong way.”