Shiva Purana
त्रिवक्त्रो यो हि रुद्रा क्षः साक्षात्साधनदस्सदा । तत्प्रभावाद्भवेयुर्वै विद्याः सर्वाः प्रतिष्ठिताः ६७ ।
A Rudrākṣa with three faces always bestows means of enjoyment. As a result of its power all lores become firmly established.
english translation
trivaktro yo hi rudrA kSaH sAkSAtsAdhanadassadA । tatprabhAvAdbhaveyurvai vidyAH sarvAH pratiSThitAH 67 ।
hk transliteration by Sanscript