What is the ruling regarding dreams in which a Muslim sees the Messenger commanding or forbidding him, or sees Allah revealing to him or speaking to him to do something or abstain from a forbidden act? And are these dreams like commands in reality, and would he be sinful or disbelieving if he did not act upon them?

Seeing Allah in a dream is permissible. As for seeing the Prophet, peace and blessings be upon him, it is true if the visionary sees him in his established form, for Satan cannot impersonate him. If the vision confirms a legal matter or prohibits something unlawful, the accountable individual may feel comforted by it. Disregarding what the vision indicates does not necessitate disbelief, but rather a sin, if what was abandoned was obligatory or what was done was legally prohibited. However, if the vision contradicts the Sharia (definition), it should not be heeded, and the reliance is on the texts of revelation.