Hadith.831 - It was narrated from the Yāsir al-Khadim that He said:
"Abu al-Hasan (as) passed by me while
I was praying on a piece of ṭabarī (a mat) upon which I had placed something.
Imam (as) said to me: 'Why do you not prostrate on it? Is it not from what the earth produces?'"