A story tells that two friends were walking through the
desert. During some point in the journey, they had an
argument and one friend slapped the other one in the face.

The one who got slapped was hurt,
but without saying anything, he wrote in the sand:
"TODAY MY BEST FRIEND SLAPPED ME IN THE FACE".

They kept walking until they found an oasis where
they decided to take a bath. The one who had been
slapped got stuck in the mire and started drowning, but his
friend saved him. After he recovered from the
near drowning, he wrote on a stone:

'TODAY MY BEST FRIEND SAVED MY LIFE".

The friend who had slapped and saved his best friend asked
him, "After I hurt you, you wrote in the sand and now you
write on a stone, why?"

He replied, "When someone hurts us, we should write it down in sand where the winds of forgiveness can erase it away, but when someone does something good for us, we must engrave it in stone, where no wind can ever erase it."