Shiva Purana
ब्रह्मोवाच ॥ आराध्य गिरिजां देवीं प्रार्थयन्तु सुराश्शिवम् ॥ योनिरूपा भवेच्चेद्वै तदा तत्स्थिरतां व्रजेत् ॥ ३२ ॥
Brahmā said:— Let the gods propitiate goddess Pārvatī and pray. If she can assume the form of the vaginal passage that penis will become steady.
english translation
brahmovAca ॥ ArAdhya girijAM devIM prArthayantu surAzzivam ॥ yonirUpA bhaveccedvai tadA tatsthiratAM vrajet ॥ 32 ॥
hk transliteration by Sanscript