On the authority of Abu Hamzah Anas bin Malik (may Allah be pleased with him) — the servant of the Messenger of Allah (peace and blessings of Allah be upon him) — that the Prophet (peace and blessings of Allah be upon him) said:
None of you [truly] believes until he loves for his brother that which he loves for himself. [Al-Bukhari][Muslim]
Reference: 40 Hadith Nawawi 13
English translation: Hadith 13