Ibn Buraidah narrated that his father said:
"The Messenger of Allah said: 'Allah has commanded me to love four people, and He told me that He also loves them.' He was asked: 'O Messenger of Allah, who are they?' He said: ''Ali is one of them,' and he said that three times, 'and Abu Dharr, Salman and Miqdad.'" (ID)
English reference (ID): Vol. 1, Book 1, Hadith 149 (ID)
Arabic reference (ID): Book 1, Hadith 154 (ID)