Issue 890...
Issue 890: * There is no harm in offering prayers in a car or a boat, or on railway train or other vehicles, while they are motionless. And if they do not cause excessive swaying to the body, when they are in motion, one can pray in them. Issue 891: Prayers offered on a heap of wheat, or barley, or any other similar thing, which cannot remain steady, is void. The Third Condition: A person should offer prayers at a place where he sees the possibility of completing the prayers.
To pray at a place where one cannot complete the prayers, because of strong winds, or heavy rains or a teeming crowd, will render Salat void, even if one somehow manages to finish the prayers. Issue 892: If a person offers prayers at a place where it is forbidden to stay, like, under a roof which is about to collapse, his prayers are in order, though he will have committed a sin.
Issue 893: * To pray on an object upon which it is haraam to step, or sit, like a carpet upon which the name of Allah is drawn or written, will render prayers void, if the action is meant to displease Allah. The Fourth Condition: The ceiling of the place where one prays should not be so low, that one may not be able to stand erect, nor should the place be so small, that there may be no room for performing Ruku or Sajdah.
Issue 894: If a person is forced to offer prayers at a place where it is not at all possible to stand, he will pray while sitting. And if it is not possible to perform Ruku and Sajdah, he should perform them by head signs. Issue 895: * One should not offer prayers in front of the graves of the holy Prophet, and the holy Imams, if it entails irreverence, otherwise there is no harm in it.
The Fifth Condition: If the place where one wishes to pray is najis, it should not be so wet that its moisture would reach the body or the dress of the person praying. But, if the place where one places one's forehead while performing Sajdah, is najis, the prayers will be void, even if that place is dry. And the recommended precaution is that the place where one offers prayers should not be najis at all.
The Sixth Condition: As an obligatory precaution, women should stand behind men while praying. At least, her place of Sajdah should be in line with his thighs, when in Sajdah. Issue 896: * If a woman stands in line with man, or in front of him in Salat , and both of them begin together, they should repeat their prayers. And the same applies if one of them starts earlier than the other.