It was narrated that 'Ali said:
"The Messenger of Allah said: 'The screen between the Jinn and the nakedness of the sons of Adam is that when a person enters the Kanif, he should say: Bismillah (in the name of Allah).'" (IT)
English reference (IT): Vol. 1, Book 1, Hadith 297 (IT)
Arabic reference (IT): Book 1, Hadith 314 (IT)