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 drowning, but the 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?