Shiva Purana
विचार्य्य सर्वशास्त्राणि धर्मांश्चैवाप्यनेकशः॥ शिवरात्रिव्रतमिदं सर्वोत्कृष्टं प्रकीर्तितम्॥ ९८॥
After considering all Śāstras, and the sacred rites enjoined by these Śivarātrivrata, has been glorified as the most excellent.
english translation
vicAryya sarvazAstrANi dharmAMzcaivApyanekazaH॥ zivarAtrivratamidaM sarvotkRSTaM prakIrtitam॥ 98॥
hk transliteration by Sanscript