'Wolves' in the Bible

"Beware of the false teachers--men who come to you in sheep's fleeces, but beneath that disguise they are ravenous wolves.

"Remember it is I who am sending you out, as sheep into the midst of wolves; prove yourselves as sagacious as serpents, and as innocent as doves.

Remember that I am sending you out as lambs into the midst of wolves.

I know that, when I am gone, cruel wolves will come among you and will not spare the flock;