Silsilat al-Ahadith al-Sahihah

Zuhair bin Muawiyah narrates from his wife, who heard from Malika bint Umar. The narrator also mentioned that during the caliphate of Sayyiduna Umar bin Khattab (may Allah be pleased with him), the owners were given back their goats. In any case, Malika suggested to her (the use of) cow's ghee for some ailment (as a remedy) and said that the Messenger of Allah (peace and blessings be upon him) said: "The milk of cows is a cure, their ghee is medicine, and their meat is disease."

It is narrated from Sayyiduna Abdullah (may Allah be pleased with him) that the Noble Prophet (peace and blessings of Allah be upon him) said: "Allah Almighty has sent down a cure for every disease except old age. Make sure to use the milk of cows, for they graze on every kind of tree."

It is narrated from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that the Noble Prophet (peace and blessings be upon him) said: "You should use the milk of cows, for they eat from every kind of tree, (and their milk) is a cure for every disease."