The hadith of Salma, the maidservant of the Messenger of Allah (peace and blessings be upon him), in which she said

The Shaykh : As for the following, it is valid, and it is his statement: And from Salma, the maidservant of the Messenger of Allah (peace and blessings be upon him), she said: No one ever complained to the Messenger of Allah (peace and blessings be upon him) of a headache except that he would say: , and no one ever complained of pain in his legs except that he would say: .
This hadith contains a new benefit compared to the preceding hadiths, in that it shows, first, that the Prophet (peace and blessings be upon him) prescribed cupping for the head for the pain a person complains of, and likewise he prescribed applying henna to the legs for one who has pain in them. This application of henna has become forgotten today, as we mentioned to you in the previous lesson, due to people’s ignorance of the Sunnah, first, and their immersion in foreign Western medicine, second. These two causes combined led people to turn away from treatment by Prophetic medicine, including cupping, of which we spoke somewhat in the previous lesson. Now, from this comes the command of the Messenger (peace be upon him) to apply henna to the legs if they are afflicted with pain.
The scholar Ibn al-Qayyim (may Allah have mercy on him) has a specific section in his book *Zad al-Ma'ad* on Prophetic medicine, in which he speaks about—approximately—everything that came in the Sunnah regarding this Prophetic medicine, especially what is established from the Prophet (peace and blessings be upon him), such as these hadiths of which you have heard some. He mentions the benefits of henna and says that they are proven. It is not possible to refute such a statement from someone like Ibn al-Qayyim, because he was a man who grew up and was raised upon the Book and the Sunnah, which purify the minds of those raised upon them. Therefore, we can only accept his statement regarding the benefit of henna as an established fact. The common proverb among us says: "Ask the experienced one, not the doctor." How much more so if he is both experienced and a doctor? He mentions among the benefits of applying henna to the legs, which the Messenger of Allah (peace and blessings be upon him) commanded with great emphasis, that I believe the lack of attention by some Islamic countries to this matter is either due to their ignorance of it or their neglect of it. Many of them were afflicted in the past with blindness due to smallpox. Ibn al-Qayyim says that it is proven that if a child is initially afflicted with this smallpox and his legs are applied with henna, he will not be afflicted with blindness; it served as a barrier between him and being afflicted with blindness. We know of countries among the Arab countries where this disease and ailment is common, and it appears that the cause is the effects of that disease which are observed on the faces of those...
This is, in reality, among the misfortunes of neglecting the Sunnah, whether in study or practice, or both. We must learn this Sunnah and act upon it, and ask the people of knowledge about it.