Shiva Purana
एकवक्त्रः शिवः साक्षाद्भुक्तिमुक्तिफलप्रदः । तस्य दर्शनमात्रेण ब्रह्महत्या व्यपोहति ६४ ।
A Rudrākṣa of a single face is Śiva Himself. It bestows worldly pleasures and salvation. The sin of brahmin-slaughter is washed off at its mere sight.
english translation
ekavaktraH zivaH sAkSAdbhuktimuktiphalapradaH । tasya darzanamAtreNa brahmahatyA vyapohati 64 ।
hk transliteration by Sanscript