Sahih Muslim
The Book of Vision (Kitab Al-Ruya)
Book Number: 029 / Hadith Number: 5628
Allah's Messenger (may peace; be upon him) said: The vision of a Muslim which he sees or which is shown to him, and in the hadith transmitted on the authority of Ibn Alushir (the words are):" The pious dream is the forty-sixth part of Prophecy."