Shiva Purana
एतावत्तु शिवज्ञानमेतावत्परमं पदम् ॥ यदोंनमश्शिवायेति शिववाक्यं षडक्षरम् ॥ २० ॥
The Śivajñāna, is as extensive as the expression of Śiva, the six-syllabled mantra, ‘Oṃ Namaḥ Śivāya’.
english translation
etAvattu zivajJAnametAvatparamaM padam ॥ yadoMnamazzivAyeti zivavAkyaM SaDakSaram ॥ 20 ॥
hk transliteration by Sanscript