Issue No.635- If a person has water but due to shortage of time, begins offering prayer with tayammum, and while he is offering prayer he loses the water he possessed, he can perform the subsequent prayers with the same tayammum.
Issue No.639- If the things which were mentioned in the previous issue are not found, he should do tayammum on dust which settles on the clothes, etc., and if it is not found either, he should do tayammum on mud. And if none of these things is available he should, on the basis of obligatory precaution, perform prayer without tayammum, and later on should perform the prayer as qaḍā; such a person is called “Fāqid al-Ṭahūrayn”, i.e., one who lacks both water and earth or suchlike on which tayammum is allowed.
Issue No.647- It is better to avoid performing tayammum on filthy earth, deep earth and roadsides, or the saline earth on which a layer of salt has not settled over. If, however, a layer of salt has covered the earth, tayammum on it is void. If the earth is so filthy that one fears that he would become sick by performing tayammum on it, one should, as an obligatory precaution, offer prayer without tayammum and offer the qaḍā later.
Issue No.638- Tayammum can also be done on lime-stone or gypsum, marble, black stones and similar stones. However, tayammum on jewellery stones, like agate and turquoise, is void. The obligatory precaution is that tayammum should not be done on plaster or quick-lime and also on bricks and earthenware.
Issue No.641- If something like straw, on which tayammum is void, is mixed with earth and sand, tayammum cannot be made using it. However, if that thing is so insignificant that it may be considered to have disappeared into the earth or sand, then tayammum on it is valid.
Issue No.643- Performing tayammum on an earthen wall is valid and the recommended precaution is that if dry earth or soil is available, tayammum should not be performed on moist earth or soil.
Issue No.656-If a person cannot perform tayammum himself, he should have someone assist him; the assistant should strike or put (if striking is not possible) the hands of that person on earth and then assist him [physically] to perform tayammum by his own hands and if this is not possible, the assistant should strike his hands on an object on which tayammum is valid and then pass them over that person's forehead and hands.
Issue No.655- If a person has a wound on his forehead, the palms or the backs of his hands and it is bandaged with a cloth or something else which cannot be removed or is harmful if removed, he should perform tayammum in the same condition.
Issue No.944- In every rak‘at after the rukū‘ of the obligatory or recommended prayers, two sajdahs should be performed; if a person, intentionally or forgetfully, omits or adds two sajdahs, his prayer is void. However, if he adds or omits one sajdah forgetfully, his prayer does not become void.
Issue No.295- It is permissible to perform wuḍū from a pool or a canal which is built in the precincts of the shrine of the holy Imams (as) or their descendants that used to be a graveyard, as long as one does not know that the land has been endowed as a graveyard.
Issue No.640- If a person does not have water, but has snow or ice, he should, if possible, melt it into water and perform wuḍū or ghusl.
Issue No.287- Performing wuḍū with the water whose owner had allowed its use before and one does not know whether he has changed his mind or not, is valid.
