Abu Qatada reported Allah's Messenger (ﷺ) as saying:
The good vision are from Allah and the evil dreams are from the satan. If one sees a dream which one does not like, one should spit on one's left side and seek the refuge of Allah from the satan; it will not do one any harm, and one should not disclose it to anyone and if one sees a good vision one should feel pleased but should not disclose it to anyone but whom one loves.
Reference: Sahih Muslim 2261 f
In-book reference: Book 42, Hadith 6
USC-MSA web (English) reference(deprecated numbering scheme): Book 29, Hadith 5618