Shiva Purana
विद्याकलास्वघोरं च तथा ब्रह्मसु पञ्चसु ॥ लिंगभागेषु पीठोर्ध्वं बीजिनं कारणत्रये ॥ १६ ॥
The five Brahmans are also terrible in the arts of knowledge. The seeds are placed above the dough in the parts of the penis for three reasons.
english translation
vidyAkalAsvaghoraM ca tathA brahmasu paJcasu ॥ liMgabhAgeSu pIThordhvaM bIjinaM kAraNatraye ॥ 16 ॥
hk transliteration by Sanscript