There was once a rabbit who had three friends: a monkey, a jackal, and an otter. For a special holiday, the four animals decided that they would all honor the gods by feeding the poor and performing other acts of charity. When the holiday arrived, the otter found some fish and the jackal found a pot of milk. The monkey, meanwhile, collected some mangoes and suggested that they give the fish, milk, and mangoes to a hungry beggar as an act of charity.
The rabbit, on the other hand, had nothing but grass to offer. He did not think that grass would be enough to satisfy a hungry beggar, so he decided that he would offer up his own body as food.
When the god Indra heard about this, he was amazed by the rabbit's devotion. He came down to earth, disguised as a beggar, and asked the rabbit for food. The rabbit was delighted by this request and asked the beggar to build a fire where the rabbit could roast himself as a holy offering. Indra built a fire and the rabbit shook his fur carefully to make sure there were no insects hiding there; he did not want for a flea or any other insect to have to die in the fire with him.
Then, without hesitation, the rabbit jumped into the fire, but the fire did not burn him! Indra revealed himself to the rabbit and praised his dedication. "Dear rabbit," the god said, "you have shown that you are the most devoted of all animals, and I will honor you by placing you in the moon."
That is why, if you look closely, you can see a "rabbit in the moon," a sign that honors the rabbit for all eternity.