مُسْنَدُ أَحْمَدَ
Musnad Ahmad 3498
Musnad of 'Abdullah bin al-'Abbas bin 'Abdul-Muttalib from the Prophet
It was narrated from Ibn ‘Abbas (رضي الله عنه): A sheep belonging to Maimoonah died, and the Prophet (ﷺ) said: "Why don't you make use of its hide?” They said: It is maitah (i.e., it died of natural causes and was not slaughtered properly). He said: "Tanning the hide purifies it.”
Musnad Ahmad 3521A saheeh, hadeeth; this is a da'eef isnad]