Shiva Purana
अथवाशेषकल्याणगुणैकधन ईश्वरः ॥ शिव इत्युच्यते सद्भिश्शिवतत्त्वार्थवादिभिः ॥ ३० ॥
Or maybe the Lord is the only wealth of the remaining auspicious qualities. He is called Shiva by the virtuous who speak the truth and meaning of Shiva.
english translation
athavAzeSakalyANaguNaikadhana IzvaraH ॥ ziva ityucyate sadbhizzivatattvArthavAdibhiH ॥ 30 ॥
hk transliteration by Sanscript