Ibn Buraidah narrated that his father said: "The Messenger of Allah (ﷺ) 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.'"
Source: sunnah.com
Other translations
Arabic
حَدَّثَنَا إِسْمَاعِيلُ بْنُ مُوسَى، وَسُوَيْدُ بْنُ سَعِيدٍ، قَالاَ حَدَّثَنَا شَرِيكٌ، عَنْ أَبِي رَبِيعَةَ الإِيَادِيِّ، عَنِ ابْنِ بُرَيْدَةَ، عَنْ أَبِيهِ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ " إِنَّ اللَّهَ أَمَرَنِي بِحُبِّ أَرْبَعَةٍ وَأَخْبَرَنِي أَنَّهُ يُحِبُّهُمْ " . قِيلَ يَا رَسُولَ اللَّهِ مَنْ هُمْ قَالَ " عَلِيٌّ مِنْهُمْ " . يَقُولُ ذَلِكَ ثَلاَثًا " وَأَبُو ذَرٍّ وَسَلْمَانُ وَالْمِقْدَادُ " .
sunnah.com