The Abhidhamma Pitaka is the third division of the Tipitaka, the sacred scriptures of Buddhism, the other parts being the Sutta Pitaka and the Vinaya Pitaka. It is made up of seven books – the Dhammasaïgani, the Vibhaïga, the Dhàtukathà, the Puggalapa¤¤atti, the Kathàvatthu, the Yamaka and the Paññhàna. An eighth book called the Mahàdhammahadaya has been lost. All the books of the Abhidhamma Piñaka are later than both the Sutta and the Vinaya Pitakas and may have been composed several hundred years after the Buddha’s passing. Tradition attributes them all to the Buddha himself but there is no mention of this in the Abhidhamma Pitaka itself nor is there any mention of the Abhidhamma Pitaka in either the Sutta or the Vinaya Pitakas. However, there is nothing in the Abhidhamma Pitaka that contradicts the Buddha’s teachings; the difference is of approach, not content. See also: Abhidhamma.
Guide to the Abhidhamma Pitaka, Nyanaponika, 1950