Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) says that the Prophet (peace and blessings be upon him) was asked about a mouse falling into ghee or fat, and he said: "If the ghee is solid, throw away what is around it." They asked: What if it is not solid? He said: "Benefit from it, but do not use it for eating."
What is correct from Ibn Umar is that this is his own statement, mawquf (stopping at him), not marfu' (attributed to the Prophet).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الضحايا / 19626