Shiva Purana
भगेन सहितं लिंगं भगंलिंगेन संयुतम् । इहामुत्र च भोगार्थं नित्यभोगार्थमेव च १०४ ।
The phallus is united with vagina and vagina is united with phallus. For the sake of perpetual enjoyment here.
english translation
bhagena sahitaM liMgaM bhagaMliMgena saMyutam । ihAmutra ca bhogArthaM nityabhogArthameva ca 104 ।
hk transliteration by Sanscript