Minda has a good point about them being raised together, but ferrets do eat meat and they have been known to attack a rabbit.
When Buck had the ferret in his care for a short time, Mrs. had saidthat the rabbits were very skiddish and uncomfortable with the ferretaround.
Although some animals adjust, some never can quite make that adjustmentto being friends as nature dictates them to be predator/prey.
-Carolyn