The Book of Vision (Kitab Al-Ruya)
Muslim :: Book 29 : Hadith 5617
Abu Salama reported Allah's Messenger (may peace be upon him) as saying: I used to see dreams, but the hadith transmitted on the authority of Laith b. Nu'man, the words of Abu Salama at the concluding part of the hadith are not mentioned. Ibn Rumh has reported in the hadith:" He (one who sleeps) should change the side on which he had been lying before."