He was asked about praying in sandals and similar footwear.

He replied:

Praying in sandals and similar footwear, such as the jumjum, madās, zarbūl and other kinds, is not disliked; rather, it is recommended. It is established in the Sahīh that “the Prophet—may Allah bless him and grant him peace—used to pray in his sandals.” In the Sunan, he is reported to have said:

“The Jews do not pray in their sandals, so differ from them.”

Thus, he commanded praying in sandals to differ from the Jews. If they are known to be free of ritual impurity, praying in them is not disliked, by agreement of the Muslims. If, however, they are definitely known to be impure, one must not pray in them until they have been purified.

The correct view, however, is that rubbing sandals against the ground purifies them, as stated in the Sunnah, whether the impurity is feces or something else. The soles of sandals repeatedly come into contact with impurity, so they are comparable to the urinary and anal openings. Since removing impurity from those openings with stones is established by the Sunnah through mass transmission, the same applies here.