If a deceased person appears in a dream and speaks, is what he says considered to be true?
All perfect praise be to Allaah, The Lord of the worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.
Please note that not all dreams that a person has in his sleep are true. As a matter of fact, some dreams may be the result of Satanic tampering. This also includes seeing dead people and talking to them during sleep.
Allaah Knows best.
You can search for fatwa through many choices