Silsilat al-Ahadith al-Sahihah

It is narrated from Sayyiduna Sahl bin Sa’d (may Allah be pleased with him) that the Messenger of Allah (peace and blessings of Allah be upon him) said: “The importance of a believer to the people of faith is like the importance of the head to the body. A believer feels pain at the afflictions of the people of faith, just as the head feels pain from the illness of the body.”