Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.007B.

All of these are considered pure. Concerning the bones of dead animals, az-Zuhri said, “I have met some scholars of the preceding generations who used such objects for combs and pots for oil, and they did not see anything wrong in that.” This is related by al-Bukhari. Said Ibn ‘Abbas, “The client of Maimunah was given a sheep as charity, and it died. The Messenger of Allah, upon whom be peace, passed by it and said, ‘Why do you not remove its skin, treat it and put it to use?’ She said, ‘It is dead’ (i.e., it has not been slaughtered properly). He said to her, ‘Only eating it is forbidden.”‘ This is related by the group. Ibn Majah attributes the incident to Maimunah and her client. Al-Bukhari and an-Nasa’i do not mention treating the skin. It is reported from Ibn ‘Abbas that he recited: “Say (O Muhammad): “In all that has been revealed to me, I do not find anything forbidden to eat; if one wants to eat thereof, unless it be carrion, or blood poured forth, or swine flesh…” (al-An’am 145). Then he said, “What is forbidden is its meat. As for its skin, skin used for water-skins, teeth, bones, fur and wool, they are permissible.” This is narrated by Ibn Munzhir and Ibn Hatim. Similarly, its rennet and milk are considered pure. This is supported by the fact that when the companions conquered Iraq, they ate the cheese of the Magians which was made from rennet, although their slaughtered animals were considered the same as ‘dead animals.’ It is confirmed from Salman al-Farsi that when he was asked about cheese, clarified butter and pelts, he said, “What is permissible is what Allah made permissible in His book. What is forbidden is what Allah made forbidden in His book. What he omits, He has pardoned for you.” It is well-known that he was being asked about the cheese of the Magians, as Salman was ‘Umar’s deputy in Mada’in, Iraq.