Musannaf Ibn Abi Shayba 16:308

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Abu Bukayr, from Ikrimah, who said: A leper clung to Ibn Abbas. I said to him, "You are clinging to a leper?" He said, "Let him be, for perhaps he is better than me and you."