Shiva Purana
अस्मात्पंचाक्षरं जज्ञे बोधकं सकलस्यतत् । आकारादिक्रमेणैव नकारादियथाक्रमम् २१ ।
From this also is born the five-syllabled mantra (Namaśśivāya). It indicates all knowledge. The syllables “NA” etc. follow the order of the syllables “A” etc.
english translation
asmAtpaMcAkSaraM jajJe bodhakaM sakalasyatat । AkArAdikrameNaiva nakArAdiyathAkramam 21 ।
hk transliteration by Sanscript