Sayyiduna Abdullah bin Amr (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "Whoever buys a ram, or is given a ram as a gift, should divide it into three portions and eat one portion each day on an empty stomach. If he wishes he may melt it, and if he wishes he may eat it as it is." The narrator says: What the Prophet (peace and blessings be upon him) meant was that this be done with the fat tail of the ram, and that it be used as a remedy for sciatica.
Al-Tabarani recorded it. He says: the word aslahu means to melt it. All the narrators of this report are thiqat (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطب / 8303