Hadith 142
Narrated Anas: Whenever the Prophet went to answer the call of nature, he used to say, "Allah-umma inni a`udhu bika minal khubuthi wal khaba'ith i.e. O Allah, I seek Refuge with You from all offensive and wicked things (evil deeds and evil spirits).
Hadith 5061
Narrated Jundub: The Prophet said, "Recite (and study) the Qur'an as long as you agree about its interpretation, but when you have any difference of opinion (as regards its interpretation and meaning) then you should stop reciting it (for the time being)'