This is how I heard. At one time, the Blessed One was living at the city of Rājagaha, in the Bamboo Park, the Squirrel Garden. During those days, Bhante Lakkhaṇa and Bhante Mahāmoggallāna were living on the Gijjhakūṭa Mountain. One day, in the morning, Bhante Mahāmoggallāna dressed in his robes, took his bowl and double-layered robe and went to Bhante Lakkhaṇa and said to him, “Come, friend Lakkhaṇa, let us go to the city of Rājagaha for alms.”
“Alright, friend,” Bhante Lakkhaṇa replied. Then, as he was coming down from Gijjhakūṭa Mountain, Bhante Mahāmoggallāna smiled at a certain place. Bhante Lakkhaṇa asked him, “Why, friend Moggallāna, did you smile?”
“Friend Lakkhaṇa, this is not the suitable time for that question. Ask me that question when we meet the Blessed One.”
Then, Bhante Lakkhaṇa and Bhante Mahāmoggallāna walked for alms in the city of Rājagaha. After they returned from their alms round, they had their meal. Then, they went to the Blessed One, worshipped himrespectfully and sat down to one side. Bhante Lakkhaṇa asked Bhante Mahāmoggallāna, “This morning, while you were coming down from the Gijjhakūṭa Mountain, Bhante Mahāmoggallāna smiled. Why, friend Moggallāna, did you smile?”
Bhante Moggallāna replied, “This morning, friend, as I was coming down from the Gijjhakūṭa Mountain, I saw a skeleton moving through the air. Vultures, crows, and hawks were chasing after it. They were pecking at it between the ribs, stabbing it, and tearing it apart. The skeleton was crying out in pain. I thought then, ‘It is unusual, indeed! It is amazing, indeed! That there exists such a being, that there exists such a non-human, that there exists such a life.”
Then, the Blessed One said to the monks, “Monks, there are disciples who have gained the divine eye and special knowledge. They can know, see, and witness such a non-human. Monks, in the past, I, too, saw that being, but I did not speak of it. If I had spoken about it, there might have been some people who wouldn’t believe my words. If they had not believed my words, it would have led them to their harm and suffering for a long time.”
The Blessed One continued, “Monks, that non-human being used to be a cattle butcher in this same city of Rājagaha. As a result of that bad kamma, he was boiled in hell for many years, for many hundreds of years, for many thousands of years, for many hundreds of thousands of years. As a remaining result of that same kamma, he has been reborn as a ghost and is experiencing such terrible pain.”