Grand Ayatollah Wahid Khorasani answers a question on dreams:
Acting upon the instructions given in a dream
Question: My brother sees a man in his dream that gives him nice instructions, tells him good things and sometimes tells him about the near future. Recently he has told him in a dream that after a short while he would die and this has lead to my brother becoming depressed and uneasy. Are his words reliable and can his instructions be acted upon?
Answer: Instructions which are contained in the holy teachings of Islam and that have been explained in ‘The book of Practical laws’ (risalah amaliye) should be acted upon and the speech of a person other than the most learned Mujtahid is not a valid proof (Hujjat). In addition, continue reciting Surah Nas, Surah Falaq, Surah Ikhlas and Surah Kafirun.
source : hawzahnews