Answer: kindness
Explanation: 
one never knows 
how far a word of kindness goes;
one never sees 
how far a smile of friendship flees.
down, through the years,
the deed forgotten reappears.
One kindly word 
the souls of many here have stirred.
Man goes his way 
and tells with every passing day,
until life's end,
once unto me he played the friend;
We cannot say 
what lips are praising us to-day. 
We cannot tell
whose prayers ask God to guard us well.
But kindness lives 
Beyond the memory of him who gives.