The Al-Muwatta, 'The Approved,' which was said to have been regarded by Imam Shafi'i, may Allah be pleased with him, to be the soundest book after the Noble Qur'an.

The first formulation of Islamic Law based on the behaviour of the people of Madinah during the time of the great Companions, Al-Muwatta is the blueprint for a just and radiant society: the earliest, clearest, cleanest record of early Islam. It is divided into 61 books on different subjects, each book containing many Ahadith. The numbering system used by Imam Malik, may Allah be pleased with him,  is consecutive per book.

Imam Malik's Muwatta (the well-trodden path) is a collection of two items:

The sayings and deeds of Prophet Muhammad, may Allah bless him and grant him peace, (also known as the Sunnah).
The reports of the Prophet's, may Allah bless him and grant him peace, sayings and deeds are called Ahadith.
The legal opinions and decisions of the Prophet's, may Allah bless him and grant him peace, Companions, their successors, and some later authorities.