in their sandals and leather socks, and would pray there despite this possibility. Yet they were not encouraged to take the precaution these people have introduced. Their error in this is therefore clear.

They may distinguish between the two by saying: “The ground becomes pure through sunlight, wind, and transformation, whereas matting does not.”

The response is: Even if this is true, it applies only to lighter impurity.

This becomes clear from the third point: It is not recommended to search for impurity that is not apparent, nor to guard against it merely because it might exist when there is no outward evidence of its presence. Even if some jurists among Ahmad’s followers and others have said that it is recommended to guard against anything doubtful without qualification, this is a weak opinion. It is established that ʿUmar ibn al-Khattāb, may Allah be pleased with him,

“He and a companion passed through a place, and water from a gutter fell on his companion. His companion called out, ‘Owner of the gutter, is your water pure or impure?’ ʿUmar said to him, ‘Owner of the gutter, do not tell him, for he is not required to know.’”

Thus, ʿUmar forbade him from answering because his companion had burdened himself with an inquiry he had not been commanded to make. This may rest on a principle: the legal consequences of impurity apply only when one is aware of it. If someone prays with impurity on his body or clothing and only discovers it after the prayer, he is not obliged to repeat it, according to the sounder of the two scholarly opinions. This is the position of Mālik and others, and of Ahmad according to the stronger of the two reports from him. This applies whether he had known about the impurity and then forgotten it, or had been unaware of it from the outset, because of the previously cited report