For I know. Paul doth now exhort the Ephesians to watch diligently, by the necessity, which is a most sharp prick. For he saith that "grievous wolves are ready to invade the sheepfold." This is a thing always incident to the Church to be hated of wolves. Wherefore, there is no time to sleep. But the more and the more hurtful those be who break in, the more watchful must the pastors be. For God doth sometimes release some part of trouble, that the flock may be fed quietly and peaceably; and as when the weather is fair and clear, the sheep are fed more safely in the fields, and there is more danger when the air is cloudy and dark; so the Church of God hath sometimes some fair weather granted to it. After that cometh a troublesome time, which is more fit for the subtilty [1] of wolves. Therefore, Paul doth mean, that it standeth them upon to be more watchful than they have been hitherto, because greater dangers hang over their heads. But the question is, how Paul knew this? First, we need not doubt of this, but that his presence was of great force to drive away wolves; and no marvel, if the power of the Spirit, which shineth in the ministers of Christ, do bridle the wicked so that they dare not utter their poison; yea, if that heavenly light do drive away much darkness of Satan. Therefore, seeing that Paul did know that the malice of Satan was kept under for a time by his industry, he doth easily foretell what will happen after his departure, though it be likely he was certified by the Lord, through the spirit of prophecy, that others might be admonished by him, as we see it came to pass. Howsoever it be, so often as faithful pastors go away, let us learn that we must beware of wolves, whom they can hardly drive from the sheep-cots, though they watch most narrowly.

Footnotes

1 - "Insidiis," the snares.

For I know this - By what he had seen in other places; by his knowledge of human nature, and of the dangers to which they were exposed; and by the guidance of inspiration.
After my departure - His presence had been the means of guarding the church, and preserving it from these dangers. Now that the founder and guide of the church was to be removed, they would be exposed to dissensions and dangers.
Grievous wolves - Heavy βαρεῖς bareis, strong, mighty, dangerous wolves - so strong that the feeble flock would not be able to resist them. The term "wolves" is used to denote "the enemies of the flock - false, and hypocritical, and dangerous teachers." Compare Matthew 10:16.
Enter in among you - From abroad; doubtless referring particularly to the Jews, who might be expected to distract and divide them.
Not sparing the flock - Seeking to destroy the church. The Jews would regard it with special hostility, and would seek to destroy it in every way. Probably they would approach them with great professed friendship for them, and expressing a desire only to defend the laws of Moses.

After my departing - Referring, most likely, to his death; for few of these evils took place during his life.
Grievous wolves - Persons professing to be teachers; Judaizing Christians, who, instead of feeding the flock, would feed themselves, even to the oppression and ruin of the Church.

(9) For I know this, that after my departing shall grievous wolves enter in among you, not sparing the flock.
(9) A prophecy of pastors that would immediately degenerate into wolves, against those who boast and brag only of a succession of persons.

For I know this,.... By divine revelation:
that after my departing; either out of this world, or after his leaving them now, and proceeding on, his journey:
shall grievous wolves enter in among you; false teachers, comparable to wolves, for their craft and cunning, and for their greedy, covetous, and voracious dispositions; and who would be very grievous, troublesome, and even intolerable to them; these, he knew, would enter privily, at an unawares, into their churches, and set up themselves for preachers, without being called or sent:
not sparing the flock; fleecing it instead of feeding it, making merchandise of it, and like the Pharisees, under religious pretences, devour widows' houses, and drain the purses of men; and having as little compassion upon their souls, poisoning them with their errors and heresies, subverting their faith, and bringing them into swift ruin and destruction, as much as would in them lie.

after my departing shall grievous wolves enter in among you--Two classes of coming enemies are here announced, the one more external to themselves, the other bred in the bosom of their own community; both were to be teachers, but the one, "grievous wolves," not sparing, that is, making a prey of the flock; the other (Acts 20:30), simply sectarian "perverters" of the truth, with the view of drawing a party after them. Perhaps the one pointed to that subtle poison of Oriental Gnosticism which we know to have very early infected the Asiatic churches; the other to such Judaizing tendencies as we know to have troubled nearly all the early churches. See the Epistles to the Ephesians, Colossians, and Timothy, also those to the seven churches of Asia (Revelation. 2:1-3:22). But watchfulness against all that tends to injure and corrupt the Church is the duty of its pastors in every age.

Grievous wolves - From without, namely, false apostles. They had, not yet broke in on the Church at Ephesus.