—may Allah bless him and grant him peace—with an admonition that brought tears to our eyes and made our hearts tremble. Someone said: ‘O Messenger of Allah, this seems like a farewell admonition. What instructions do you give us?’ He replied: ‘I counsel you to listen and obey. Whoever among you lives on will witness much disagreement. So adhere to my Sunnah and the Sunnah of the upright, rightly guided caliphs after me. Hold firmly to it and cling to it with your molar teeth. Beware of newly introduced matters, for every innovation is misguidance.’”

In the two Sahīh collections, ʿĀ’ishah narrated that the Prophet, may Allah bless him and grant him peace, said:

“Whoever introduces into this matter of ours something that does not belong to it, it is rejected.”

Another wording reads:

“Whoever performs a deed that does not accord with our way, it is rejected.”

In Sahīh Muslim, Jābir narrated that the Messenger of Allah, may Allah bless him and grant him peace, used to say in his sermon:

“The finest speech is the Book of Allah, and the best guidance is the guidance of Muhammad. The worst matters are those newly introduced, and every innovation is misguidance.”

As for the practice of many people of having mats placed in the mosque on Friday or other days before going there themselves, this is prohibited by the unanimous agreement of Muslims; indeed, it is unlawful. Is a person’s prayer on such a mat valid? Scholars have two opinions on this, because by laying down that mat he has wrongfully appropriated a space in the mosque and prevented other worshippers who arrive before him from praying there.

If someone prays in a space in the mosque while preventing others from praying there, is his prayer like prayer on usurped land? There are two views. As for prayer on land