Anas binMalik said:
"I heard the Messenger of Allah (ﷺ) saying:'Thecure for sciatica is the fat from the tail of a Bedouin sheep (orwild sheep), which should be melted and divided into three parts, onepart to be taken each day on an empty stomach.'" (ID)
English reference (ID): Vol. 4, Book 31, Hadith 3463 (ID)
Arabic reference (ID): Book 31, Hadith 3592 (ID)