مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3775
Musnad of Abdullah bin Mas'ood
It was narrated that Abu Hurairah (رضي الله عنه) said: The Messenger of Allah (ﷺ) said: “Whoever sees me in a dream it is as if he has seen me when awake, for the Shaitan cannot appear in my form."
Musnad Ahmad 3798Its isnad is saheeh]