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 drowning, but the friend saved him. After he recovered from nearly drowning, he wrote on a stone, "Today my best friend saved my life."
His friend asked him, "After I hurt you, you wrote in the sand and now, you write on a stone, why?" The other friend replied "When someone hurts us we should write it down in sand where 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."