(39, 40) And this know, that if the goodman of the house . . .--Better, "if the master of the house." See Notes on Matthew 24:43-44, where the words are almost identical.

Verses 39, 40. - And this know, that if the goodman of the house had known what hour the thief would come, he would have watched, and not have suffered his house to be broken through. Be ye therefore ready also: for the Son of man cometh at an hour when ye think not. The Lord abruptly changes the scene of his parable imagery, and with another striking and vivid example enforces his teaching on the subject of the urgent necessity of his servants keeping a sleepless and diligent watch and ward against his coming again in judgment. Very deeply must this image of the Lord's sudden return, as a thief breaks into the house in the still hours of the night, have impressed itself on the hearts of the awe-struck, listening disciples, for we find in the case of SS. Paul and Peter the very words and imagery, and in the case of St. John the imagery again made use of (see 1 Thessalonians 5:1, 2; 1 Peter 3:10; Revelation 3:3; Revelation 16:15). The meaning of the simile is obvious. The disciples and all followers of Jesus would do well to remain always on the watch for the second advent of the Lord. The time of that awful return was unknown, never could be known; men, however, must not be deceived by the long tarrying; the clay of the Lord would surely come on the world as a thief in the night.

12:22-40 Christ largely insisted upon this caution not to give way to disquieting, perplexing cares, Mt 6:25-34. The arguments here used are for our encouragement to cast our care upon God, which is the right way to get ease. As in our stature, so in our state, it is our wisdom to take it as it is. An eager, anxious pursuit of the things of this world, even necessary things, ill becomes the disciples of Christ. Fears must not prevail; when we frighten ourselves with thoughts of evil to come, and put ourselves upon needless cares how to avoid it. If we value the beauty of holiness, we shall not crave the luxuries of life. Let us then examine whether we belong to this little flock. Christ is our Master, and we are his servants; not only working servants, but waiting servants. We must be as men that wait for their lord, that sit up while he stays out late, to be ready to receive him. In this Christ alluded to his own ascension to heaven, his coming to call his people to him by death, and his return to judge the world. We are uncertain as to the time of his coming to us, we should therefore be always ready. If men thus take care of their houses, let us be thus wise for our souls. Be ye therefore ready also; as ready as the good man of the house would be, if he knew at what hour the thief would come.And this know,.... The Ethiopic version reads, "this only know"; only take notice of this one thing, and it may be of some use to direct you in your conduct how to behave during the absence of your Lord, until the time he shall come again:

that if the good man of the house had known what hour the thief would come; that is, if the owner, or master of the house, whose the goods in the house are, could by any means know what time of the night the thief would come to break into his house, in order to plunder it, and carry off his goods:

he would have watched; either he himself in person, or he would have set a watch about his house, or in it:

and not have suffered his house to be broken through; either the door to be broken up, or the wall to be dug through, but by a guard about it, or within it, would have prevented such a design. And so in like manner, could it be known in what time Christ would come, either to the destruction of Jerusalem, or at death, or to judgment, every thoughtful, prudent man that should know it, would be upon his guard, that he might not be surprised with it; and though the precise time could not be known, yet inasmuch as the thing itself is certain, it became all the servants of Christ to be watching for it; See Gill on Matthew 24:43.