"Musnad" (7), and [Imam Ahmad] (8) said: It is a good chain of narration, narrated by Yahya ibn Sa'id from Shu'bah, (9) from al-Hakam, from Abd al-Rahman ibn Abi Layla, from Abdullah ibn Ukaym. In another wording: The letter of the Messenger of Allah, peace and blessings of Allah be upon him, came to us one or two months before his death (10), and it is an abrogator of what preceded it, because it was at the end of the life of the Prophet, peace and blessings of Allah be upon him, and its wording indicates that the concession had preceded it and that this is subsequent to it, due to his saying: "I had granted you a concession." And one only follows the latest and then the latest of the commands of the Messenger of Allah, peace and blessings of Allah be upon him.

If it is said: This is a mursal (discontinuous) narration, because it is from a letter whose bearer is unknown. We say: The letter of the Prophet, peace and blessings of Allah be upon him, is like his spoken word. Were it not for that, the Prophet, peace and blessings of Allah be upon him, would not have written to anyone, yet he wrote to the kings of the peripheral regions and others, and the proof was binding upon them by it, and the message reached them. If it were not a proof, the response would not have been binding upon them, nor would the message have been communicated by it, and they would have had an excuse for neglecting the response, due to their ignorance of the bearer of the letter and his reliability. Abu Bakr al-Shafi'i narrated, with his chain of narration, from Abu al-Zubayr, from Jabir, that the Prophet, peace and blessings of Allah be upon him, said: "Do not benefit from anything of the carcass" (11). Its chain of narration is hasan (sound). And because it is a part of the carcass, it is therefore forbidden, due to His saying, the Exalted: {Forbidden to you is the carcass} (12). Thus, it does not become pure through tanning, like meat, and because it was forbidden upon death, so it remained impure as it was before tanning.