– Another legal implication is the permissibility of tayammum (dry ablution) and that its cause is one of two things:
• Either the absence of water, as in His statement, “and you find no water” (4:43);
• Or the likelihood of harm from using it, as in His statement, “or if you are ill” (4:43). Therefore, any harm that would befall a servant through the use of water licenses him to turn to tayammum, and such harms are many in kind. The verse’s mention of travel is only because travel is a situation in which water is often lacking—just as pledges are restricted to travel—not because travel on its own is a sufficient reason for tayammum, as some people have imagined; that notion clashes with “and you find no water.”

– Another point: tayammum may be performed with anything that lies on the earth’s surface, whether it raises dust or not, so long as it is pure (ṭayyib) and not impure (najis) in this context.

– Tayammum is confined to two limbs: the face and the hands.

– When “hands” is mentioned without qualification, it refers to the palms, as in the verse on theft; when it is qualified—as in the ablution verse “up to the elbows”—the qualification must be observed.

– The verse also alludes to what obliges minor purification, namely:
• answering the call of nature, i.e., anything exiting from either of the two passages;
• and touching women out of desire.
The Sunnah adds the requirement of ablution after deep sleep, touching the private parts, and—subject to scholarly disagreement—after eating camel meat.