Musannaf Ibn Abi Shayba 16:176

Abu Bakr narrated to us, he said: Abd al-Wahhab al-Thaqafi narrated to us, from Bard, from Makhul, that a mouse fell into oil, so they asked the Prophet, may God bless him and grant him peace, and he said: "Use it for lighting, and do not eat it." And Makhul used to say: "If it falls into ghee and it is solid, it and what is around it should be discarded, and what is other than that should be eaten. But if it is melted, nothing of it should be eaten."