Why Muslims never eat pork.

Prophet Mohamed was crossing the desert with some of his men. They were going from Mecca to Medina. After about five hours of walk, the prophet and his men were thirsty. No water was to be found in the area. Suddenly, they saw a wild pig in front of them.
Mechanically, they started following the animal as if it had told them to do so.
Unexpectedly, the animal reached a stream where the prophet and his disciples could drink and continue their travel towards Medina. The travelers were very happy because of what the animal had done. In order to show his gratitude to this pig, the prophet decided immediately that Muslims should not eat porlc.

Vocabulary
Unexpectedly: contre toutes attentes    
A stream: un ruisseau