A story tells that two friends were walking through the desert. During somepoint of the journey they had an argument, and one friend slapped the other one in the face.
TODAY MY BEST FRIEND SLAPPED ME IN THE FACE.
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 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.