It wasnarrated that Khuzaimah bin Jaz' said:
"I said: 'O MessengerofAllah, I have come to you to ask you about the vermin of the earth.What do you say about mastigures?' He said: 'I do not eat themand Ido not forbid them.' I said: 'I will eat of that which youhave notforbidden. But why (do you not eat them), O Messenger ofAllah?' Hesaid: 'One of the nations was turned into beasts and Ilooked at thiscreature and was uncertain.' I said: 'O Messengerof Allah, what doyou say about rabbits?' He said: 'I do not eatthem and I do notforbid them.' I said: 'I will eat of that whichyou have notforbidden. But why (do you not eat them), O Messenger ofAllah?' Hesaid: 'I have been told that it menstruates.'"
English reference: Vol. 4, Book 28, Hadith 3245
Arabic reference: Book 28, Hadith 3368