Mjadala wa kina kuhusu misingi ya aina hii ya ibada (^ibadah) umeshughulikiwa katika sura tano. Sura ya 1 inahusu dalili za wajibu wake — ni nani aliyewajibika nayo na lini; Sura ya 2 inahusu kubainisha matendo yake; Sura ya 3 inahusu kubainisha kitu ambacho hufanywa nacho, yaani maji; Sura ya 4 inahusu kubainisha mambo yanayobatilisha ibada hiyo; na Sura ya 5 inahusu kubainisha vitu ambavyo inaweza kufanywa navyo.

A comprehensive discussion of the principles of this (type of) worship (^ibadd) is covered in five chapters. Chapter 1 relates to the evidence of its obligation— on whom it is obligatory and when; Chapter 2 is about the identification of its acts; Chapter 3 is about the identification of that with which it is performed, that is, water; Chapter 4 is about the identification of factors nullifying it; and Chapter 5 is about the identification of things with which it can be performed.

23 Najisi (uchafu wa kidini) umegawanywa na wanazuoni wa fiqhi katika aina mbili: najisi halisi (haqiqiya) na najisi ya kihukmu au ya kisheria (hukmiya). Neno hadath hutumika kwa najisi ya kisheria au ya kihukmu, huku neno khabath likitumika kwa najisi halisi. Hadath inaweza kuwa ndogo, ambayo huondolewa kwa wudhuu, au kubwa (janaba na hedhi), ambayo huondolewa kwa kuoga (ghusl). Vilevile, najisi halisi inaweza kuwa nzito (mughallaza) au nyepesi (mukhaffafa).