All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Whoever sees the Prophet in a dream, then he has truly seen him, because Satan does not assume his image.
The condition for that is that he should see him in his image that was mentioned in the Ahaadeeth.
Whoever sees someone in a dream with descriptions other than this image, and the person in the dream mentioned to him that he is the Messenger of Allah, then it is not definite that it is truly the Prophet .
However, whoever saw his honorable person in his image that was reported in Islamic texts, then it is definitely him .
There is no sign for this except for the person to see him, and he is certain that it is him according to what we mentioned of his image based on his description in Islamic texts.
For more benefit on seeing the Prophet, sallallaahu ‘alayhi wa sallam, in a dream, please refer to Fataawa 8896, 23595, 23970, and in dreams">91030.
Allah Knows best.