Two friends were walking through a desert. During some point of the journey, they had an argument and one of them slapped the other in the face. Although it hurt, he didn't say anything, but rather 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 same one who got slapped got stuck in the mire and started drowning, but the friend saved him. After recovering from nearly drowning, he wrote on a stone: "Today my best friend saved my life".

His friend then asked him, "After I hurt you, you wrote in the sand and now on a stone, why?" The other 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. That is to say, learn to write your hurts in the sand and to carve your benefits in stone."