It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him), he said: A believer is a mirror to his brother; when he sees a fault in him, he corrects it.
Hadith Referenceالادب المفرد / كتاب الانبساط إلى الناس / 238
Hadith Gradingالألبانی:حسن
Hadith Takhrij«حسن : أخرجه ابن وهب فى الجامع : 203 و أبوالشيخ فى التوبيخ : 57»