The Acts 20:28-31

Take heed to yourselves, and to the whole flock, wherein the Holy Ghost hath placed you bishops, to rule the church of God, which he hath purchased with his own blood. I know that, after my departure, ravening wolves will enter in among you, not sparing the flock. And of your own selves shall arise men speaking perverse things, to draw away disciples after them. Therefore watch, keeping in memory, that for three years I ceased not, with tears to admonish every one of you night and day.