Shiva Purana
रुद्रा क्षश्चाष्टवक्त्रश्च वसुमूर्तिश्च भैरवः । धारणात्तस्य पूर्णायुर्मृतो भवति शूलभृत् ७३ ।
A Rudrākṣa with eight faces is called Vasumūrti and Bhairava. By wearing it a man lives the full span of life. After death he becomes the Trident-bearing lord (Śiva).
english translation
rudrA kSazcASTavaktrazca vasumUrtizca bhairavaH । dhAraNAttasya pUrNAyurmRto bhavati zUlabhRt 73 ।
hk transliteration by Sanscript