From Sahih Bukhari (Hadith 6993):
Narrated Abu Huraira:I heard the Prophet (ﷺ) saying, "Whoever sees me in a dream will see me in his wakefulness, and Satan cannot imitate me in shape." Abu `Abdullah said, "Ibn Seereen said, 'Only if he sees the Prophet (ﷺ) in his (real) shape
Reference: Bukhari 6993