A good dream may bring comfort and encouragement, but it cannot alone decide what is obligatory or forbidden, or determine another person’s rights. Established teachings from the Qur’an and Sunnah and reliable scholarship remain the standards for such judgments.
For instance, a dream may encourage someone toward a known good deed. It would not justify claiming someone else’s property or imposing a newly invented obligation.
The statement فَإِنَّ الشَّيْطَانَ لَا يَتَمَثَّلُ فِي صُورَتِي specifically negates Satan’s ability to assume the Prophet’s form.