In Sahih Muslim, al-Numān ibn Bashīr (may Allah be pleased with him) reported that the Messenger of Allah (peace and blessings be upon him) said: “The Muslims are like a single person: if his eye suffers, his whole body suffers; and if his head suffers, his whole body suffers.”1
It is also authentically reported from the Prophet (peace and blessings be upon him) in the hadith of Abū Mūsā al-Asharī (may Allah be pleased with him), who said that the Messenger of Allah (peace and blessings be upon him) said: “A believer is to another believer like a building, each part supporting the others.”2
Al-Tabarānī narrated that Abū Mūsā al-Asharī (may Allah be pleased with him) heard the Prophet (peace and blessings be upon him) say: “You will not truly believe until you show mercy to one another.” They said, “O Messenger of Allah, all of us are merciful.” He replied: “It does not mean merely the mercy one of you shows to his companion, but mercy toward all people—mercy that encompasses everyone.”3
There are many hadiths conveying this meaning. A Muslim should therefore observe the rights of his fellow Muslims, desire good for them, treat them with mercy and compassion, and pray that they be granted success, sound judgment, goodness, prosperity, righteousness, and steadfastness.