Abu Qataadah Radiyallahu 'Anhu reports that Rasulullah Sallallahu 'Alayhi Wasallam said:
"Whomsoever sees me, that is, in a dream, has seen that which is a fact". (DE)
App reference (DE): Book 56, Hadith 7 (DE)
English reference (DE): Book 55, Hadith 394 (DE)
Arabic reference (DE): Book 56, Hadith 412 (DE)