SB 9.1.32

tad idaṁ bhagavān āha
 priyāyāḥ priya-kāmyayā
sthānaṁ yaḥ praviśed etat
 sa vai yoṣid bhaved iti
Word for word: 
tat — because; idam — this; bhagavān — Lord Śiva; āha — said; priyāyāḥ — of his dear wife; priya-kāmyayā — for the pleasure; sthānam — place; yaḥ — anyone who; praviśet — will enter; etat — here; saḥ — that person; vai — indeed; yoṣit — female; bhavet — shall become; iti — thus.
Translation: 
Thereupon, just to please his wife, Lord Śiva said, “Any male entering this place shall immediately become a female!”