Shiva Purana
तस्मादस्य प्रसादार्थं नैमिषे सत्रयोगतः ॥ यजध्वं दीर्घसत्रेण रुद्रं परमकारणम् ॥ १९ ॥
Hence, in order to propitiate him perform the Satra. Worship him who is the ultimate cause, perform Satra in Naimiṣa extending over a long period.
english translation
tasmAdasya prasAdArthaM naimiSe satrayogataH ॥ yajadhvaM dIrghasatreNa rudraM paramakAraNam ॥ 19 ॥
hk transliteration by Sanscript