The story why Buddhists do not eat beef

I was chatting with 2 customers yesterday to pass the time while my hands are busy processing their orders into the computer. I was explaining the story of why Buddhists do not eat beef, when I got struck. I actually forget what is the title of "The Emperor of Heaven", or commonly known as "Yu Huang Da Di" in mandarin. In the end, I just referred him as the Guy managing Heavens. Hahaha..

In case you are interested of the story, here it goes:

Once upon a time, a great man dies. His spirit floated to Heavens and the Emperor of Heavens decided to let him reincarnate as a bull. The great man refused and told the Emperor that he would suffer under the hands of humans if he became a bull.

The Emperor assured him that he would not suffer and so the great man finally agreed. So the great man reincarnate into a bull and was treated badly by humans. His owner made him plough the fields everyday from dawn to dusk, feeding the bull with only water and dry grass. The suffering only ended when the bull died from old age/exhaustion. Even then, his body was not left alone as the owner cut him up and eat his meat.

Seeing this, the Emperor of Heavens then gave a declare that all who worshipped him and his Gods should be forbid from eating beef. Thus, the reason why the Buddhists does not eat beef.

p.S. It was years ago when I read this story from a book so my version may be slightly different but the plot is more or less the same :p