Abdur Rahman bin 'Abdullah عبد الرحمن بن عبد الله بن مسعود الهذلي · The Book of Purification and its Sunnah

"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).'"