مُسْنَدُ أَحْمَدَ
Musnad Ahmad 2513
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated that Sa'eed bin Jubair said: 'Abdullah - and 'Uthman did not say anything more than 'Abdullah - told me: The Messenger of Allah (ﷺ) said: "Whoever sees me in a dream has truly seen me, for the Shaitan can not appear in my image.”
Musnad Ahmad 2525Saheeh, because of corroborating evidence; this is a da'eef