The Prophet ﷺ said, "Whoever sees me in a dream will see me while awake, or it is as if he saw me while awake. Satan cannot take my form."This is the wording of Muslim. Bukhari added that Ibn Sirin said, "That is when he sees him in his true form."
عن النبي ﷺ قال: من رآني في المنام فسيراني في اليقظة، أو لكأنما رآني في اليقظة، لا يتمثل الشيطان بي وهذا لفظ مسلم، وزاد البخاري قال ابن سيرين: إذا رآه في صورته.
Bukhari related it in the Book of Interpretation of Dreams (6993) and Muslim in the Book of Vision (2266-11) through two routes from Zuhri, Abu Salama bin Abdul-Rahman told me that Abu Hurairah said, then he mentioned the hadith.Bukhari also related it in the Book of Knowledge (110) and Muslim in the Introduction (3) through another route from Abu Awana, from Abu Husayn, from Abu Salih, from Abu Hurairah, from the Prophet ﷺ, who said, "Take my name but do not take my kunya, and whoever sees me in a dream has indeed seen me, for Satan cannot take my form, and whoever deliberately lies about me let him take his seat in the Fire." This is the wording of Bukhari, and Muslim related it in abridged form.Muslim also related it in the Book of Vision (2266-10) through another route from Hammad bin Zayd, who said, Ayub and Hisham told us, from Muhammad, from Abu Hurairah, with the wording, "Whoever sees me in a dream has indeed seen me, for Satan cannot take my likeness."As for his saying, "he will see me while awake," meaning during his lifetime ﷺ, Allah the Exalted grants him the ability to migrate to him and to see him ﷺ while awake, in clear sight. But after his death, no one is able to see him while awake, and if anyone claims to have done so, he is lying. This is why another wording came, "as though he sees me while awake," meaning that seeing him in a dream resembles seeing him while awake, not that one actually sees him awake in clear sight after his death ﷺ.The scholars said, the Prophet ﷺ was singled out in that seeing him in a dream is sahih, and Satan was prevented from taking his form so that he could not lie speaking through his tongue in sleep, just as he was prevented from taking his form while awake, as an honor to him.Khasais Al-Nabi ﷺ by Ibn Mulaqqin (p. 202)