The Prophet ﷺ said, "Allah has not sent down any disease without also sending down a cure for it, so make use of cow's milk, for the cow grazes on every kind of plant."
حدثنا عبد الرحمن بن مهدي حدثنا سفيان عن يزيد أبي خالد عن قيس بن مسلم
أن النبي ﷺ قال إن الله عز وجل لم يضع داء إلا وضع له شفاء فعليكم بألبان البقر فإنها ترم من كل الشجر
Its chain of transmission is sahih. It is found in Ibn Hibban with the same wording, 340, no. 1398, Mawarid, and Hakim graded it sahih, 4/403, and Dhahabi agreed with him. The well-known wording is "Allah has not sent down any disease..." in the Sahih collections.