Is sequence or order mandatory in Wudu (ablution)?
Chapter on the Obligation of Purification
Al-Mughni
Book of Purification
Primary text
Sequence in Wudu is obligatory according to Ahmad, concerning whom no difference of opinion is known. This is also the position of Al-Shafi'i, Abu Thawr, and Abu Ubayd. The evidence supporting obligation rests on the structure of the relevant Quranic verse, where the placement of the wiped part (head) between two washed parts implies a mandatory sequence, as Arabs do not separate similar elements without significant purpose, which here is the sequence. Furthermore, the verse was revealed to explain what is obligatory, omitting Sunan (recommended acts). An order inherently implies obligation. Moreover, every narration of the Prophet's (peace be upon him) ablution describes it in order, and he explicitly stated, "This is the ablution upon which Allah does not accept prayer except with it," meaning with the like of it.
Supporting text
A dissenting view, attributed to a narration from Ahmad, holds that sequence is not obligatory. This view is the position of Malik, Al-Thawri, and the Ashab al-Ra'y (supporters of rational opinion). It is also related from Sa'id ibn al-Musayyab, 'Ata', Al-Hasan, 'Ali, Makhluf, Al-Nakha'i, Al-Zuhri, and Al-Awza'i concerning one who forgets to wipe his head but finds moisture on his beard; they permit wiping the head with it without requiring the washing of the feet to be redone. Ibn al-Mundhir favored this view because the command to wash the limbs is connected by the conjunction 'wa' (and), which does not necessitate order, meaning any order of washing suffices for compliance. Furthermore, 'Ali and Ibn Mas'ud stated they did not mind which limb they started with, and Ibn Mas'ud explicitly permitted starting with the feet before the hands.