When workers brought their landlord a basket of cucumbers from the first harvest, the generous landlord distributed cucumbers to all the workers and then to the household servants, not keeping even one for himself.
The landlord then turned to a servant who was eating a cucumber and smiling happily. "Let me have a taste," he said to the servant.
The servant gave him the cucumber and, to his surprise, it was bitter.
"How can you smile eating something so bitter?" the landlord asked.
"The memory of sweet gifts you gave us in the past made me smile," the servant replied.
Inspired by: Under the Sufi's Cloak: Stories of Abu Said and His Mystical Teaching by Mohammad Ali Jamnia and Mojdeh Bayat
Notes: This story is on p. 38 of the book. You can find out more about Abu Said at Wikipedia. There is a similar story in Rumi which is told about Luqman as a devoted slave who smiles as he eats a bigger melon; see Tales from the Masnavi by A. J. Arberry, story 37.