Sayyidunā Nuʿmān ibn Bashīr رضي الله عنه narrated: “The Noble Prophet ﷺ said: ‘The similitude of the Muslims in their mutual love and mercy and affection for each other is like one body. When one limb of the body is afflicted with pain, the entire body is afflicted with insomnia and fever.” [Ṣaḥīḥ Bukhārī #6011, Ṣaḥīḥ Muslim #2586]
This means that our ears are separate limbs of our bodies, our nose, eyes and teeth are all separate limbs. Similarly, each limb is in its respective position. Our body is made up of all these different limbs. However, despite the limbs being separate, due to being all positioned firmly in one body, the connection between them is such that if one is wounded in one’s finger and it swells and is filled with pus, then consequently, one’s entire body will feel the pain at night. The entire body will experience fever, will remain awake and he will be unable to sleep.
The eyes will never think that the finger is wounded and it is distant from me, so what connection does it have with me? I will sleep comfortably. Similarly, the person’s foot also does not think what does the finger have to do with me? Rather, due to this, the pain runs through the entire body and due to this wound, the entire body remains awake and feels the pain.
Look! The different limbs in one body, each limb’s function is different in its respective place. Despite this, by being in one body, there is such a connection between them to the extent that if the smallest limb is in pain, the largest of limbs also becomes restless for it. The entire body is afflicted with fever and insomnia. The entire body is unable to sleep and the effect of the fever is on the entire body. Restlessness overcomes the entire body.
Similarly, the relation of ʾīmān and Islām has made all believers like one body. There should be such a connection of mutual love, compassion and affection which prevails among them that it should be like how the entire body remains awake for the wound on the smallest finger.
Hazrat Muftī Aḥmed Khānpūrī Ṣāḥib حفظه الله ونفعنا بعلومه وفيوضه وصحبته
Similarly, our ʾīmānī connection and relation demands that no matter how far another believer resides, if he is afflicted by hardships, another believer should also feel his pain within his heart. Meaning, since he has been afflicted, it is as though we have also been afflicted. Additionally, there should be no deficiency on our part in the effort required to remove his pain. This is the connection which all believers should have with each other.
[Dars Riyāḍuṣ Ṣāliḥīn Vol. 4 Pg.192-194 by Hazrat Muftī Aḥmed Khānpūrī Ṣāḥib حفظه الله ونفعنا بعلومه وفيوضه وصحبته ]