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". (JA)
App reference (JA): Book 56, Hadith 7 (JA)
English reference (JA): Book 55, Hadith 394 (JA)
Arabic reference (JA): Book 56, Hadith 412 (JA)