Chapter: Tayammum1
Tayammum is valid only when eight conditions are met: intention, being Muslim, sanity, discernment, and having cleansed oneself after relieving oneself—whether by washing (istinjāʾ) or wiping with stones (istijmār).
The sixth condition is that the time for the prayer has begun; tayammum is not valid for a prayer before its time, nor for a supererogatory prayer performed during a period in which voluntary prayers are forbidden.
The seventh is the inability to use water, either because it cannot be found or because using it would cause harm.
Water must still be offered to any thirsty2 human being or to a respected3 animal.
Whoever finds only a small amount of water that is insufficient for full purification must use it for whatever part it will cover—this is obligatory—and then complete the rest with tayammum4.
If a traveller reaches water when the remaining time is too short—or knows that his turn to use it will not come until after the time has expired—he may fall back on tayammum, whereas a non-traveller may not, even if the time subsequently elapses.
Anyone who, while the prayer time still remains, pours the water away or passes it by when he could have performed wuḍūʾ5 and knows he will not find any other commits a sin; nevertheless, if he then performs tayammum and prays, he does not have to repeat the prayer.
If someone in a state of minor impurity discovers an impurity on his body or clothing and has only a small amount of water that is insufficient, it becomes obligatory to wash