5. Ali has narrated from his father from Ibn Abi ‘Umayr from Muhammad ibn Ishaq ibn ‘Ammar from abu al-Hassan Musa (a.s.) who has said the following
“The Imam (a.s.) was asked about the surfaces on which a mention of Allah, the Most Majestic, the Most Holy, is written. The Imam said, ‘Wash it clean.’”