Arabic text
عن المِقدام بن معدي كرب رضي الله عنه عن النبي صلى الله عليه وسلم قال: «إِذَا أَحَبَّ الرَّجُلُ أَخَاهُ فَلْيُخْبِرْهُ أَنَّهُ يُحِبُّهُ».
Translation
Al-Miqdām ibn Ma‘di Karib (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "When a man loves his brother, he should tell him that he loves him."
Explanation
The Prophet (may Allah's peace and blessings be upon him) demonstrates one of the means that strengthens the bond between the believers and spreads love among them: If a person loves his fellow Muslim, he should tell him that he loves him.
Source: HadeethEnc.com