A story goes that two friends were walking through the desert. At some point on their journey they had an argument, one friend slapping the other in the face.
The one who was slapped was hurt. Without saying anything he wrote in the sand, “Today my best friend slapped me in the face.”
They kept on 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 to drown, but his friend saved him. After he recovered from that near-drowning experience, 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?” The other replied, “When someone hurts us we should write it down in sand where winds of forgiveness can erase. But, when someone does something good for us, we must engrave it in stone where the winds can never erase.”