“A mother holds her children’s hands for a while, but their hearts forever” (or “Mothers hold their children’s hands for a while, but their hearts forever”) is a popular Mother’s Day saying that has been printed on many images. Both “A Mother holds her children’s hands for a while—their hearts forever” and “Mothers hold their children’s hands for just a little while—their hearts forever.” were printed in 1978 newspapers. Authorship is unknown.
 
 
9 May 1978, The Daily Northwestern (Oshkosh, WI), “Food for Thought” by June Jenkins, pg. 13, col. 4:
A Mother holds her children’s hands for a while—their hearts forever.
 
13 August 1978, Indianapolis (IN) Star, “Death Notices,” sec. 3, pg. 11, col. 4:
“Mothers hold their children’s hands for just a little while—their hearts forever.”
     
31 July 1987, Philadelphia (PA) Daily News, “A Pretty Fair Time” by Dan Geringer, pg. 62:
Home and fine arts will be back this year. Perhaps we will see a sampler to equal last year’s heart-accented work by Ann Herrara of Trenton: “A Mother Holds Her Children’s Hands For Awhile . . . Their Hearts Forever.”
 
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Thaddeus K. Smith and Bertha Heyne:
Their ancestors and descendants, including the families of Bard, Downing, and Veach
By Margaret E. Herrick
LaGrangeville, NY:  M.E. Herrick
1989
Pg, 79:
Here is a little poem which came from my children: “Mothers hold their children’s hands for just a little while; Their hearts, forever.”
 
29 July 1992, Sun Sentinel (Fort Lauderdale, FL), “Sophie;s Choice: The test came back positive for HIV” by Jill Young Miller, pg. 1E:
On a wall in another room hangs a saying: “A mother holds her children`s hands for a while ... their hearts forever.”
 
27 June 1993, Orange County Register (Santa Ana, CA), “On Books: La Habra author draws on tragedy to create success” by Valerie Takahama, pg. F23:
Barbara Johnson, a La Habra author of inspirational books, has scored a first with three books on the Publishers Weekly paperback religious list in June - and all three are in the Top 5.
(...)
Her works are peppered with inspirational messages that have helped her cope with difficult times, such as “If you grasp tomorrow with faith, you know the handle won’t fall off” and “Mothers hold their children’s hands for a while . . . their hearts forever.”
 
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Mothers are Like Miracles:
They Make Everything Possible
By Janet Lanese
New York, NY: Fireside
1998
Pg. 55:
A mother holds her children’s hands for a while, their hearts forever.
Anonymous
 
Google Books
The Quotable Mom:
Appreciation from the Greatest Minds in History
Edited by Brooke Jorden
Familius LLC (Famlilius.com)
2014
Pg. ?:
“Mothers hold their children’s hands for a short while, but their hearts forever.”
—Anonymous
 
Google Books
Chicken Soup for the Soul: Thanks to My Mom:
101 Stories of Gratitude, Love, and Lessons
By Amy Newmark and Jo Dee Messina
Cos Cob, CT; Chicken Soup for the Soul Publishing, LLC
2015
Pg. ?:
Mothers hold their children’s hands for a short while, but their hearts forever.
—Author Unknown