Shiva Purana
किमन्यदिह वक्तव्यं भस्ममाहात्म्यकारणम् ॥ व्रती च भस्मना स्नातस्स्वयं देवो महेश्वरः ॥ ९६ ॥
What else need be cited to indicate the glory of Bhasma? The Vratin who has had the Bhasma-bath is lord Śiva himself.
english translation
kimanyadiha vaktavyaM bhasmamAhAtmyakAraNam ॥ vratI ca bhasmanA snAtassvayaM devo mahezvaraH ॥ 96 ॥
hk transliteration by Sanscript