Revelation 3:3

Remember therefore how thou hast received - This may refer either to some uniqueness in the manner in which the gospel was conveyed to them - as, By the labors of the apostles, and by the remarkable effusions of the Holy Spirit; or to the ardor and love with which they embraced it; or to the greatness of the favors and privileges conferred on them; or to their own understanding of what the gospel required, when they were converted. It is not possible to determined in which sense the language is used; but the general idea is plain, that there was something marked and unusual in the way in which they had been led to embrace the gospel, and that it was highly proper in these circumstances to look back to the days when they gave themselves to Christ. It is always well for Christians to call to remembrance the “day of their espousals,” and their views and feelings when they gave their hearts to the Saviour, and to compare those views with their present condition, especially if their conversion was marked by anything unusual.

And heard - How thou didst hear the gospel in former times; that is, with what earnestness and attention thou didst embrace it. This would rather seem to imply that the reference in the whole passage is to the fact that they embraced the gospel with great ardor and zeal.

And hold fast -

1. Hold fast the truths which thou didst then receive;

(2)Hold fast what remains of true religion among you.

And repent - Repent in regard to all that in which you have departed from your views and feelings when you embraced the gospel.

If therefore thou shalt not watch - The speaker evidently supposed that it was possible that they would not regard the warning; that they would presume that they would be safe if they refused to give heed to it, or, that by mere inattention and indifference they might suffer the warning to pass by unheeded. Similar results have been so common in the world as to make such a supposition not improbable, and to make proper, in other cases as well as that, the solemn threatening that he would come suddenly upon them.

I will come on thee as a thief - In a sudden and unexpected manner. See the notes on 1 Thessalonians 5:2.

And ye shall not know what hour I will come upon thee - You shall not know beforehand; you shall have no warning of my immediate approach. This is often the way in which God comes to people in his heavy judgments. Long beforehand, he admonishes us, indeed, of what must be the consequences of a course of sin, and warns us to turn from it; but when sinners refuse to attend to his warning, and still walk in the way of evil, he comes suddenly, and cuts them down. Every man who is warned of the evil of his course, and who refuses or neglects to repent, has reason to believe that God will come suddenly in his wrath, and call him to his bar, Proverbs 29:1. No such man can presume on impunity; no one who is warned of his guilt and danger can feel that he is for one moment safe. No one can have any basis of calculation that he will be spared; no one can flatter himself with any probable anticipation that he will have time to repent when God comes to take him away. Benevolence has done its appropriate work in warning him - how can the Great Judge of all be to blame, if he comes then, and suddenly cuts the sinner off?