Anas ibn Mālik (may Allah be pleased with him) reported that a man was with the Prophet (may Allah's peace and blessings be upon him) and another man passed by him. He said: "O Messenger of Allah, I love this man." The Prophet (may Allah's peace and blessings be upon him) said: "Have you told him?" He said: 'No!' He said: "Tell him." He went after him and said: "I love you for Allah's sake." He said: "May the One you love me for His sake love you!" [Sahih/Authentic] - [An-Nasaa’i - Abu Dawood - Ahmad]

عن أنس بن مالك -رضي الله عنه- أنَّ رَجُلاً كَانَ عِند النَبِيَّ -صلى الله عليه وسلم- فَمَرَّ رَجُلٌ بِهِ، فقال: يا رسول الله، أنِّي لَأُحِبُّ هَذَا، فَقَال لَهُ النَبِيُّ -صلى الله عليه وسلم-: «أَأَعْلَمْتَهُ؟» قال: لا. قال: «أَعْلِمْهُ»، فَلَحِقَهُ، فقال: إِنِّي أُحِبُّك فِي الله، فقال: أّحَبَّك الَّذِي أَحْبَبْتَنِي لَهُ. [صحيح.] - [رواه أبو داود والنسائي في الكبرى وأحمد.]