Abu Khayr reported,

I saw a fur garment on Ibn Walah al-Sabai, so I touched it. He said, "Why are you touching it? I once asked Abdullah bin Abbas a question. I said, 'We live in the Maghreb, and among us are Berbers and Magians. They bring us a ram which they have slaughtered, but we do not eat their slaughtered animals. They also bring us a waterskin in which they put fat.'Ibn Abbas said, 'We asked the Messenger of Allah ﷺ about that, and he said, Its tanning is its purification.'"

عن أبي الخير قال

رأيت على ابن وعلة السبئي فروا، فمسسته فقال: مالك تمسه؟ قد سألت عبد الله بن عباس، قلت: إنا نكون بالمغرب ومعنا البربر والمجوس، نؤتى بالكبش قد ذبحوه، ونحن لا نأكل ذبائحهم، ويأتونا بالسقاء يجعلون فيه الودك، فقال ابن عباس: قد سألنا رسول الله ﷺ عن ذلك؟ فقال: دباغه طهوره.