The Prophet, peace be upon him, said 'cleanliness is half of faith'. Wudhu is the ritual washing performed by Muslims before prayer. Muslims must be clean and wear good clothes before they present themselves before God.Wuḍhu is often translated as "partial ablution", as opposed to ghusl ("full ablution"), washing the whole body, or tayammum ("dry ablution"), replacing water with sand or dust due to its scarcity, its harmful effect on the person, or some other reason. Every Muslim must be in a state of spiritual purification before performing the daily obligatory prayers. The same state of purification must also be achieved before numerous other acts of worship, such as optional prayers, touching the script of the Qur`an and the rites of the pilgrimage (hajj) can be performed.

This book is dedicated to an analysis of seven groups of hadiths related to matters ranging from the rules concerning water used for ablution to those concerning the proof of facts in a qadi court. It has three main purposes. The first is to clarify the processes by which hadiths on a given topic were formed and developed by analyzing their isnāds and matns and by comparing them with expositions of positive law in legal manuals. Second, it seeks to explain why many hadiths exist in multiple variants and to detect the perception of traditionists about the revision of hadiths. The third purpose is to propose a methodology to estimate the extent to which traditionists accepted hadiths on a particular topic.