Section
[Obligatory elements of tayammum and its nullifiers]
Its obligatory elements are: wiping the face and the hands up to the wrists (1); specifying in one’s intention the permission to perform whatever act he is seeking to make lawful by tayammum—whether lifting a state of ritual impurity or removing a physical defilement—and, in the case of minor ritual impurity, observing the proper order and uninterrupted succession.
If he intends only ritual impurity or only defilement, the tayammum does not suffice for the other; if he intends both, it suffices.
If he intends merely a supererogatory act, or leaves the intention undefined, he may not perform an obligatory prayer with that tayammum.
If, however, he intends the obligatory prayer of the time, he may, for the whole of that time, perform both obligatory and supererogatory prayers with it (2).

Tayammum is nullified by the end of the prayer time, by anything that breaks the state for which it was performed, and by the availability of water—even if the water is found while one is actually praying, though not after completion. For someone who hopes to obtain water, delaying tayammum until the end of the prayer time is preferable.

[The manner of performing tayammum]
Its procedure is as follows: he forms the intention, recites the basmalah, then strikes clean earth once with both hands, the fingers spread apart—after removing anything like a ring—wipes his face with the inner sides of his fingers (3), then wipes his hands with his palms, interlacing the fingers.