It wasnarrated that Abu Dharr said:
"I asked the Messenger of Allah(ﷺ)about the all-black dog and he said: '(It is) a devil.'" (JA)
English reference (JA): Vol. 4, Book 28, Hadith 3210 (JA)
Arabic reference (JA): Book 28, Hadith 3331 (JA)