Prayer: Further Conditions for the Place of Prayer
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 872
In prayers and other situations, it is unlawful to turn one’s back to the grave of the Prophet (Ṣ) or the Infallible Imams (ʿA) if it amounts to disrespecting them. However, if it would not amount to disrespecting them due to there being a large distance or an obstacle like a wall between the person and the grave, then there is no problem. Of course, on its own, the distance between the person and the sacred coffin, or the cloth that is placed over it, or the sacred lattice enclosure of the tomb (ḍarīḥ), would not be sufficient for discounting any disrespectful behaviour towards them; but in either case, if the person establishes an intention to attain proximity to Allah, his prayer will be valid.
The fifth condition: If the place where a person performs prayers is impure, it must not be so wet that its moisture reaches his body or clothing, in case the impurity is of the type that invalidates prayers. However, if the place where one places his forehead is impure, the prayers are invalid even if the place is dry. And the recommended precaution is that the place where one performs prayers should not be impure at all.
The sixth condition: Based on obligatory precaution, a woman must stand behind a man at least to the extent that the place of her sajdah is level with the place of his knees when he performs sajdah.