Chapter 20, verses 29-32
29
For I know that after my departure, vicious wolves will enter in among you, not sparing the flock.
30
Men will arise from among your own selves, speaking perverse things, to draw away the disciples after them.
31
Therefore watch, remembering that for a period of three years I didn’t cease to admonish everyone night and day with tears.
32
Now, brothers, I entrust you to God, and to the word of his grace, which is able to build up, and to give you the inheritance among all those who are sanctified.
