– Another implication is that, just as tayammum is prescribed for minor ritual impurity, it is likewise prescribed for major ritual impurity, for Allah mentions it immediately after referring to the causes of both kinds of purification.

– It also follows that in tayammum the rules for minor and major purification are identical: one wipes only the two limbs—the face and the hands.

– The noble verse further shows that tayammum fully substitutes for ablution with water whenever water is unavailable or its use would be harmful. Allah Himself has allowed it to stand in water’s place and has called it a purification, and many hadiths confirm this.

From this it becomes clear that the sound view is that tayammum is not nullified by the expiration or entrance of a prayer time, nor by any of the other factors cited by many jurists. It is invalidated only by one of two things:
• the occurrence of anything that breaks ritual purity; or
• the availability of water, or the removal of the harm that had prevented its use.

– Another implication is that water whose characteristics have been altered by pure substances—even if the change is considerable—must still be used in preference to tayammum, because the phrase “and you find no water” employs an indefinite noun in a context of negation, thus covering every kind of water except impure water.

– Many scholars also deduce that anyone who is in a place without water yet suspects that water may exist nearby is required to search for it and look around before resorting to tayammum. The wording “and you find no water” can only apply after one has sought it wherever it could reasonably be found without undue hardship; this is a subtle but telling inference.