Shiva Purana
जलस्नानं मलत्यागे भस्मस्नानं सदा शुचि । मंत्रस्नानं हरेत्पापं ज्ञानस्नाने परं पदम् ७६ ।
When impurities are evacuated, a bath with water shall be performed; a bath with the ash (bhasma) is always purificatory; a bath with mantras removes sin and if a bath with knowledge is taken, the greatest goal will be reached.
english translation
jalasnAnaM malatyAge bhasmasnAnaM sadA zuci । maMtrasnAnaM haretpApaM jJAnasnAne paraM padam 76 ।
hk transliteration by Sanscript