Sahih Bukhari
Interpretation of Dreams
Volume: 009 / Book Number: 087 / Hadith Number: 124
Narrated Abu Qatada:
The Prophet said, "A good dream is from Allah, and a bad dream is from Satan. So whoever has seen (in a dream) something he dislike, then he should spit without saliva, thrice on his left and seek refuge with Allah from Satan, for it will not harm him, and Satan cannot appear in my shape."