عَنْ سَهْلِ بْنِ سَعْدٍ السَّاعِدِيِّ رَضِيَ اللَّهُ عَنْهُ يُحَدِّثُ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ قَالَ ((إِنَّ الْمُؤْمِنَ مِنْ أَهْلِ الْإِيمَانِ بِمَنْزِلَةِ الرَّأْسِ مِنَ الْجَسَدِ يَأْلَمُ الْمُؤْمِنُ لِأَهْلِ الْإِيمَانِ كَمَا يَأْلَمُ الْجَسَدُ لِمَا فِي الرَّأْسِ))
Narrated from Sayyiduna Sahl bin Sa’d Sa’idi (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: Surely, the relationship of a believer with other people of faith is like the relationship of the head with the body. A believer feels pain for other believers just as the whole body feels pain due to an illness in the head.