Shiva Purana
सम्पन्ने च तथा ज्ञाने मुक्तो भवति निश्चितम् ॥ इति चेज्ज्ञानवान्यो वै शंभुमेव सदा भजेत् ॥ ३५॥
If knowledge is attained he certainly becomes liberated. Hence if one desires to be perfectly wise one should worship Śiva alone always.
english translation
sampanne ca tathA jJAne mukto bhavati nizcitam ॥ iti cejjJAnavAnyo vai zaMbhumeva sadA bhajet ॥ 35॥
hk transliteration by Sanscript