Shiva Purana
सेयं त्रिसाधना सेवा शिवधर्मश्च कथ्यते ॥ स तु पञ्चविधः प्रोक्तः शिवेन परमात्मना ॥ ३६ ॥
This threefold service is called the holy rite of Śiva. It is of five kinds as explained by Śiva the great Ātman.
english translation
seyaM trisAdhanA sevA zivadharmazca kathyate ॥ sa tu paJcavidhaH proktaH zivena paramAtmanA ॥ 36 ॥
hk transliteration by Sanscript