Ferrets are belong to the genus Mustela, of the family Mustelidae. They are closely related to weasels, polecats, stoats and minks. Being of the family Musetlidae, they are often referred to as being a weasel.
Weasels are not rodents, but in the wild they often prey on rodents such as rabbits, mice, and rats.
Take a look at your ferrets teeth, too! You’ll see that their teeth are very similar to that of a cat or dog, just on a smaller scale. They look nothing like a rodents teeth, which need to be kept trimmed by chewing on blocks and grains.