Hadith: Adh-hib al-ba’sa rabb an-nās washfi anta ash-shāfi la shifā’ illa shifā’uk shifā’an la yughādiru saqama (Remove the harm, Lord of the people, and heal, for You are the Healer. There is no healing except Your healing, a healing that leaves behind no illness)

عَنْ عَائِشَةَ أُمِّ المؤْمنينَ رَضيَ اللهُ عنها قَالَت:
كَانَ رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ إِذَا أَتَى الْمَرِيضَ يَدْعُو لَهُ قَالَ: «أَذْهِبِ الْبَاسَ، رَبَّ النَّاسِ، وَاشْفِ أَنْتَ الشَّافِي، لَا شِفَاءَ إِلَّا شِفَاؤُكَ، شِفَاءً لَا يُغَادِرُ سَقَمًا».
[صحيح] - [متفق عليه] - [صحيح مسلم: 2191]

‘Ā’ishah, Mother of the Believers, (may Allah be pleased with her), reported:
When the Messenger of Allah (may Allah's peace and blessings be upon him) would visit a sick person, he would supplicate for him saying: "Adh-hib al-ba’sa rabb an-nās washfi anta ash-shāfi la shifā’ illa shifā’uk shifā’an la yughādiru saqama (Remove the harm, Lord of the people, and heal, for You are the Healer. There is no healing except Your healing, a healing that leaves behind no illness)."
[Authentic hadith] - [Narrated by Bukhari & Muslim] - [Sahih Muslim - 2191]

Explanation

Whenever the Prophet (may Allah's peace and blessings be upon him) visited a sick person, he would supplicate for him saying: O Allah, (remove) and eliminate (the harm) and severe sickness, (Lord of the people), their Creator, and their Sustainer, (and heal) this sick person, (for You), may You be exalted, (are the Healer). I implore You by Your name, the Healer. (There is no healing) that can occur to the sick (except Your healing) and Your well-being, (a healing) that completely (leaves behind) and retains (no illness) or any other sickness.

Benefits from the Hadith

1. The Healer is Allah Almighty while the doctor and medicine are merely means that neither benefit nor harm except by Allah's permission.
2. Visiting the sick is one of the rights among Muslims, and it is even more deserving when it comes to family members.
3. Encouraging those who visit a sick person to supplicate for him with this blessed and transmitted supplication.
4. The Prophet (may Allah's peace and blessings be upon him) practiced treatment through the Shariah-approved Ruqyah (faith-healing/incantation) with the Qur’an and good supplications. When he (may Allah's peace and blessings be upon him) became ill, he would perform Ruqyah on himself, his family members, and others who were unwell.
5. Ibn Hajar said: There is confusion in supplicating for the recovery of the sick even though illness contains expiation for sins and a source of reward, as affirmed by the Hadīths. The answer is: Supplication itself is an act of worship and does not contradict the reward and expiation of sins, for these are obtained at the onset of illness and through dealing patiently with it. The supplicator is in a win-win position: either he attains his goal or is compensated with some benefit or protection from harm—all are from the grace of Allah Almighty.