An Important Scholarly Introduction:

Before we turn to the subject at hand, I must first lay down a set of foundational rules. No one who seeks to gain fiqh (legal understanding) of the Sunnah can afford to be ignorant of them, and the very method of composition adopted here requires that they be stated at the outset, so that we may simply refer back to them whenever the occasion calls. In this way I hope to spare both myself and the reader a considerable amount of time and to free us from much unnecessary repetition, as the discerning reader will observe.