Shiva Purana
शिवनामविभूतिश्च तथा रुद्रा क्ष एव च । एतत्त्रयं महापुण्यं त्रिवेणीसदृशं स्मृतम् 1-23-१० ।
Śiva’s name, the ashes and the Rudrākṣa beads—the three are very holy and are on a par with Triveṇī॥ 1॥ (the confluence of the three holy rivers).
english translation
zivanAmavibhUtizca tathA rudrA kSa eva ca । etattrayaM mahApuNyaM triveNIsadRzaM smRtam 1-23-10 ।
hk transliteration by Sanscript