The Prophet ﷺ used to prescribe for sciatic nerve pain the fat tail of a black Arabian ram, neither too large nor too small. It was to be divided into three portions, melted, and one portion drunk each day.
أن النبي ﷺ كان يصف من عرق النساء ألية كبش عربي أسود، ليس بالعظيم، ولا بالصغير، يجزأ ثلاثة أجزاء، فيذاب، فيشرب كل يوم جزء.
Ibn Majah (3463), Ahmad (13295), and Hakim (2/292) all narrated it through Hisham bin Hassan, from Anas bin Sirin, from Anas, who mentioned it as stated. The wording given is Ahmad's, and Ibn Majah and Hakim added, "then he drinks it on an empty stomach."Hakim reported from Anas bin Sirin, who said, "I instructed a great many people to do this, he mentioned a large number, all of whom were cured by Allah's permission." In some narrations it says, "a hundred people."Hakim (4/207) also narrated it through another route from Anas bin Sirin with similar wording, but there Anas bin Malik said, "I prescribed it to more than three hundred people, all of whom recovered from it." Hakim said, "All these chains of transmission are sahih according to the criteria of the two Shaykhs."