The virtue of senna is narrated in the Sunnah.
It was narrated from Asma' bint 'Umays that the Messenger of Allaah asked her: "What do you use as a laxative?" She said: "Spurge." He said: "Hot, hot." She said: Then I used senna as a laxative and the Prophet said: "If there were anything in which there is a cure for death, it would be senna." Al-Tirmidhi, 6/254, 256. Al-Albaani said: it is Da'eef. See Hadith no. 4807 in Da'eef Al-Jaami'Administering medicine through the side of the mouth (Ladood): this means inserting the medicine with finger. The Arabic word Ladood comes from the phrase Ladeed Al-Waadi (theside of the valley). Nose drops refers to the medicine that is placed through the nose or is given by means of inhaling through the mouth. Laxatives are medicines given to make one defecate.
It was narrated that ibn 'Abbaas said: The Messenger of Allaah said: "The best medicines which you use are those which are administered through the side of the mouth, nose drops, cupping and laxatives." Narrated and classed as Hasan by Al-Tirmidhi; narrated and classed as Saheeh by Al-Haakim and by Abu Na'eem in Tibb Al-Nabawi.
It was narrated from Asma' bint 'Umays that the Messenger of Allaah entered upon her one day and she had some spurge which she was grinding. He said: "What are you going to make with that?" She said: "We drink it." He said: "If anything were to ward off death or be of benefit against death, it would be senna."How to prepare the drink
Al-Haakim said: This Hadeeth has a Saheeh Isnaad, and Al-Dhahabi agreed with him. Mustadrak Al-Haakim, from the Hadeeth of 'Umar ibn Al-Khattab.
Ibn Maajah narrated in his Sunan, in Kitaab Al-Tibb (the Book of Medicine) that Ibraaheem ibn Abi 'Ablah said: I heard Abu Ubayy ibn Umm Haraam, who had prayed with the Messenger of Allaah facing both Qiblahs, say: I heard the Messenger of Allaah say: "You should use senna and sanoot, for in them there is healing for every disease, except Al-saam." It was said: "O Messenger of Allaah , what is Al-saam?" He said: "Death." Sanoot may refer to dill or honey. Ibn Maajah, Kitaab Al-Tibb, Hadeeth no. 3457. (Translator)
The sick person should go and get some senna and put it in a vessel containing a litre of water. This should be boiled on the fire, then strained and left to cool. Then the sick person should drink three cups of it on an empty stomach. Honey may be added to sweeten it. After that the sick person will experience a strong loosening of the bowels. The effects of the drink should appear within seven hours and last up to twenty two hours, and may be accompanied by a mild stomachache, but without any infection in the intestines. When the senna drink begins to take effect, he he will void all the dirt that is in the stomach, and thus the substance used for witchcraft will be expelled - if Allaah wills. This has been tried in many cases and has been beneficial, by the bounty and grace of Allaah .
Dr. Muhammad 'Ali Al-Baar has written a paper on senna and its virtue according to the Sunnah, and he spoke a great deal about its medical benefits. Among other things he said:
Senna is regarded as a gentle stool softener and is not harmful. It works directly on the colon. It is an effective laxative and is a good medicine with no side effects, well balanced and dry. Its beneficial effects include working against depressing thoughts, cracks in the feet, tension in the muscles, the spread of hair, lice, scabies, pustules and itching. If it is cooked in olive oil and drunk, it expels putrid matter. It is also effective against pain in the back and hips. One of the features of senna is that it expels black bile and phlegm and strengthens the heart. It is also useful in the case of chronic headaches and epilepsy; it gets rid of haemorrhoids; it is useful in the case of constipation as a stool softener and laxative. There is hardly any stool softener or laxative in the pharmacy that does not contain senna. There is no doubt that senna is one of the best stool softeners available. Al-Senna Wa'l-Sanoot by Dr. Muhammad 'Ali Al-Baar.Taken from, The Jinn and Human Sickness - Remedies in the Light of the Qur'aan and Sunnah
by Dr. Abu'l-Mundhir Khaleel ibn Ibraaheem Ameen
Foreword by Waheed ibn 'Abbus Salaam Baali
Translated by Nasiruddin Al-Khattab
Edited by Dr. Abdul Ahad (Alig.)