The similitude of believers in regard to mutual love, affection, fellow-feeling is that of one body; when any limb of it aches, the whole body aches, because of sleeplessness and fever. (Using translation from Muslim 2586a)
سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ مَثَلُ الْمُؤْمِنِينَ فِي تَوَادِّهِمْ وَتَرَاحُمِهِمْ وَتَعَاطُفِهِمْ مَثَلُ الْجَسَدِ إِذَا اشْتَكَى مِنْهُ شَيْءٌ تَدَاعَى لَهُ سَائِرُ الْجَسَدِ بِالسَّهَرِ وَالْحُمَّى