Shiva Purana
विद्यार्थी पुरुषः प्रीत्या सहस्रमितपार्थिवम् । पूजयेच्छिवलिंगं हि निश्चयात्तत्फलप्रदम् ७ ।
A person who seeks learning shall with pleasure make a thousand earthen phallic images and offer worship. Certainly he will get that benefit.
english translation
vidyArthI puruSaH prItyA sahasramitapArthivam । pUjayecchivaliMgaM hi nizcayAttatphalapradam 7 ।
hk transliteration by Sanscript