Acts 20:28-31

Take heed therefore unto yourselves and to all the flock, in which the Holy Spirit has placed you as bishops to feed the congregation {Gr. ekklesia – called out ones} of God, which he has purchased with his own blood. For I know this, that after my departing, grievous wolves shall enter in among you, not sparing the flock. Also from among your own selves, men shall arise, speaking perverse things to draw away disciples after themselves. Therefore watch and remember that by the space of three years I ceased not to warn every one night and day with tears.