The Permissibility of Praying in One's Slippers

Question:
Praying in one's slippers?

Answer:
It is a recommended practice, an act of devotion, and an act of obedience, provided they are clean and sound. However, since carpets have been introduced and people have started treading on them and soiling them for others, and most people do not care about their slippers or take care of them, one should carry them and place them in a specific spot so as not to soil the carpets for others. This is because most people do not care for or take care of their slippers, and they do not have insight into this matter. Also, the early mosques had gravel and sand floors, so this did not harm them.
It is obligatory, always, not to enter the mosque except with care. One should look at his slippers when entering the mosque to ensure there is no filth in them that would soil the mosque, whether the floor is paved or the mosque has a gravel floor. He has no right to enter the mosque until he has inspected his slippers and turned them over to remove any harm from them. Then, there is nothing wrong with praying in them, just as the Prophet (peace and blessings be upon him) prayed in them.
But today, after the mosques have been carpeted and have come to have expensive rugs, where even the slightest thing affects them, and people may be repelled from praying on them or performing the congregational prayer, the believer should not repel people. Rather, he should be a helper to them in performing the congregational prayer, and he should keep his slippers in another place.