The Messenger of Allah ﷺ was asked about a mouse that had fallen into clarified butter and died. He said, "If it is solid, take it out along with what surrounds it and eat the rest. But if it is liquid, do not eat it."
حدثنا محمد بن جعفر قال حدثنا معمر قال أخبرنا ابن شهاب عن ابن المسيب
سئل رسول الله ﷺ عن فأرة وقعت في سمن فماتت فقال إن كان جامدا فخذوها وما حولها وكلوا ما بقي وإن كان مائعا فلا تأكلوه
Its chain of transmission is sahih. Bukhari related it, 1/343, no. 236, in the chapter on wudu, on what falls into impurities. Nasai related it, 7/178, in the chapter on Faraa and Atirah, regarding the mouse that falls into ghee. Abdul-Razzaq related it, 1/84, no. 278. And Ibn Hibban related it, 331, no. 1364, Mawarid.