The Messenger of Allah ﷺ said, "Allah has not sent down any disease without also sending down its cure. So make use of cow's milk, for the cow grazes on every kind of plant."
قال رسول الله ﷺ: ما أنزل الله داء إلا أنزل له دواء، فعليكم بألبان البقر، فإنها ترم من كل الشجر.
Ibn Hibban (6075), Tayalisi (366), Hakim (4/196), and Bayhaqi (9/345) all narrated it through routes from Qays bin Muslim, from Tariq bin Shihab, from Ibn Masud, who related it. Its isnad is sahih. Hakim graded it sahih according to the criterion of Muslim. There is disagreement within the isnad regarding whether it is raised (marfu) or stopped (mawquf), connected (mawsul) or disconnected (mursal), but what I have set out here is the most sahih version of it.Bazzar (2999) narrated it through the route of Muhammad bin Jabir, from Qays bin Muslim, from Tariq bin Shihab, from Abu Musa, from the Prophet ﷺ, with the same wording, placing it instead among the narrations of Abu Musa Ashari. Muhammad bin Jabir is Ibn Sayyar bin Tariq Hanafi. Abu Zura said, "His hadith is discarded." Bukhari said, "He is not strong, they speak critically of him, he narrated objectionable reports." Abu Dawud said, "He is worthless." Ibn Hibban said, "He was blind, and he would add to his books things that were not part of his hadith, and he would steal what was related to him and then narrate it as his own."As for his wording "tarumm," with the ra vowelled with damma and the mim doubled, it means "it eats," that is, the cow may eat from certain trees that serve as medicine, and their effect remains present in the milk. As for what has been narrated concerning the meat of cattle being a disease, this is not established. This is what Tabarani narrated in al-Kabir (25/42) from Ali bin Abdul-Aziz, from Ahmad bin Yunus, from Zuhayr, who said, "A woman from my family told me, on the authority of Malikah bint Amr Zaydiyyah, a descendant of Zayd bin Saad, that she said, 'I complained of a pain in my throat, so I went to her, and she gave me cow ghee.' She said, 'The Messenger of Allah ﷺ said, "Their milk is a cure, their ghee is a remedy, and their meat is a disease."'"Abu Dawud narrated it in al-Marasil (444) from Ibn Nafil, "Zuhayr narrated to us," with his isnad, presuming that Malikah bint Amr was not a companion, though a group of scholars affirmed with certainty that she was. In the isnad the woman is left unnamed, and Haythami likewise faulted it for this in al-Majma (5/90).Muhammad bin Jareer Tabari narrated it, and through his route Abu Naeem in al-Tibb (325), from Ahmad bin Hasan Tirmidhi, "Muhammad bin Musa Nasai narrated to us, Daffa bin Daghfal Sadusi narrated to us, from Abdul-Hameed bin Sayfi bin Suhayb, from his father, from his grandfather," raising it to the Prophet, "You should take cow's milk, for it is a cure, its ghee is a remedy, and its meat is a disease." Ibn Qayyim mentioned it in his Zad (4/324-325) and said, "What is in this isnad is not established."I say, in it is Daffa, with the dal vowelled with fatha followed by a doubled fa, bin Daghfal Qaysi or Sadusi. Abu Hatim said, "Daif." Al-Hafiz relied on this and said in al-Taqrib, "Daif." And Abdul-Hameed bin Sayfi bin Suhayb is "lenient in hadith," as stated in al-Taqrib.Similar in meaning is what has also been narrated from Abdul-Rahman bin Abdullah bin Masud, from his father (Ibn Masud), from the Prophet ﷺ, with comparable wording. Abu Naeem narrated it in al-Tibb (858), and Hakim narrated it (4/404) and said, "This hadith has a sahih isnad." Dhahabi followed up on this and said, "In it is Sayf bin Miskeen, whom Ibn Hibban weakened." End of quote.I say, Ibn Hibban said, "A shaykh from the people of Basra, who brings reversed reports and fabricated matters. It is not permissible to rely on him as evidence, because of his contradicting the reliable narrators in his narrations, despite how few they are." al-Majruhin (440).The conclusion regarding this is that this hadith is not sahih in any way. Rather, it contradicts the words of Allah Most High,"That they may witness benefits for themselves and mention the name of Allah on known days over what He has provided for them of sacrificial animals. So eat from them and feed the miserable and the poor." [Hajj 22:28]Cattle are among these "grazing livestock," according to the words of Allah Most High,"And of the grazing livestock are some for carrying burdens and some for slaughter. Eat of what Allah has provided for you and do not follow the footsteps of Satan. Indeed, he is a clear enemy to you. Eight mates, of the sheep two and of the goats two. Say, 'Is it the two males He has forbidden, or the two females, or what the wombs of the two females contain? Inform me with knowledge, if you are truthful.' And of the camels two and of the cattle two. Say, 'Is it the two males He has forbidden, or the two females, or what the wombs of the two females contain? Or were you present when Allah charged you with this?' Who then is more unjust than one who invents a lie against Allah to mislead the people without knowledge? Indeed, Allah does not guide the wrongdoing people." [Anam 6:142–144]Allah Most High does not command the eating of something that contains pure harm, or whose harm outweighs its benefit, just as it is also established from the Prophet ﷺ that he sacrificed a cow on behalf of his wives and commanded his companions to eat from it. He would never command his companions to eat something that contains disease, just as one does not draw near to Allah with anything that contains harm. And Allah Most High knows best.