Sahih Muslim
The Book Pertaining to Piety and Softening of Hearts (Kitab Al-Zuhd wa Al-Raqaiq)
Book Number: 042 / Hadith Number: 7136
Abu Huraira reported that the rat (is the result of) metamorphosis (of a group of Bani Isra'il) and the proof of this is that when the milk of goat is placed before it, it drinks it, and when the milk of the camel is placed before it, it would not taste it at all. Ka'b said: Did you hear it from Allah's Messenger (may peace be upon him)? Thereupon he said: Has Torah been revealed to me?