To be able to pray, we need to remove impurities from the body, cloth and place of prayer. Otherwise the prayer is invalid.
The Quran says:
‘Purify your clothing, and shun all filth!’ [74:4-5]
Washing with water is the main methods by which impurities are removed.
The Quran says:
“And We sent down from the heavens water that purifies.” [25:48]
Any other liquid substance can also be used to remove physical impurities, as long as it:
flows easily;
is itself ritually pure;
facilitates the removal of impurities.
Thus, any filth can be washed off the cloth and place of prayer to make it suitable for worship. There are also other methods of puritication, however, we are not mentioning them for the sake of brevity.
A small amount of impurity is excusable if the whole combined area is less than 2 cm in diameter (like a medium-sized coin). If the area is more than that, then the impuritites have to be removed.
As for the body, the main type of impurity is poo and urine. In the next article, we'll learn how to clean oneself properly after toilet.