Musnad Ahmad 1153:1178

'Abd al-Razzaq narrated to us, he said: Malik narrated to us, from Yazid ibn 'Abd Allah ibn Qusayt, from Ibn Thawban, from his mother, from 'Aisha: "That the Prophet, peace and blessings of Allah be upon him, commanded that the skins of dead animals be utilized if they have been tanned."