Rasendrapurana 26.35

Rasendrapurāṇa 26.35

aśuddhamanaḥśilādoṣāḥ
aśmarīmūtrakṛcchrāṇi aśuddhā kurute śilā
maṃdāgniṃ malabaṃdhaṃ ca kurute tena śodhayet