to the Prophet, may Allah bless him and grant him peace, of a church in Abyssinia, its beauty, and the images within it. He said:

“When a righteous man among those people died, they would build a place of worship over his grave and make those images inside it. Those are the worst of creation before Allah on the Day of Resurrection.”

If, however, there are no images in a church, the Companions did pray in churches. And Allah knows best.

He was asked:

Regarding someone who spreads out a prayer mat in the congregational mosque and prays on it: is what he has done an innovation or not?

He answered:

All praise is due to Allah, Lord of all worlds. As for deliberately choosing to pray on a prayer mat, this was not the practice of the early generations—the Emigrants, the Helpers, and those who followed them in righteousness. During the lifetime of the Messenger of Allah, may Allah bless him and grant him peace, they would instead pray directly on the ground in his mosque. None of them had a personal mat reserved for praying on.

It is related that when ʿAbd al-Rahmān ibn Mahdī came to Medina, he spread out a prayer mat, so Mālik ordered that he be detained. Mālik was told, “He is ʿAbd al-Rahmān ibn Mahdī.” He said, “Did you not know that spreading out a prayer mat in our mosque is an innovation?”

In the Sahīh, it is narrated from Abū Saʿīd al-Khudrī, in the account of the Prophet’s devotional retreat