It is narrated from Sayyiduna Dihyah al-Kalbi (may Allah be pleased with him); he said: A woollen cloak and a pair of leather socks were given as a gift to the Messenger of Allah (peace and blessings be upon him), and he (peace and blessings be upon him) wore them until they wore out, and he did not ask whether their leather was from a slaughtered (lawful) animal or not.
Hadith Referenceالمعجم الكبير للطبراني / باب الدال / 4185