Behold, I come quickly - That is, in the trials referred to. Compare the notes on Revelation 1:1, Revelation 1:11, Revelation 1:16.
Hold that fast which thou hast - That is, whatever of truth and piety you now possess. See the notes on Revelation 3:3.
That no man take thy crown - The crown of life appointed for all who are true believers. See the notes on 2-Timothy 4:8. The truth which is taught bore is, that by negligence or unfaithfulness in duty we may be deprived of the glory which we might have obtained if we had been faithful to our God and Saviour. We need to be on our constant guard, that, in a world of temptation, where the enemies of truth abound, we may not be robbed of the crown that we might have worn forever. Compare notes on 2-John 1:8.

Behold, I come quickly - These things will shortly take place; and I am coming with consolations and rewards to my faithful followers, and with judgments to my adversaries.
Take thy crown - God has provided mansions for you; let none through your fall occupy those seats of blessedness.

Behold, I come quickly,.... To bring on this hour of temptation on the reformed churches, which will be at the beginning of this period; to help and deliver, save and preserve the truly godly among them; to destroy antichrist, and introduce the latter day glory:
hold that fast which thou hast; either her grace in the exercise of it, as her faith, patience, &c. or rather the doctrines of the Gospel, and the ordinances of it, which she had received, as delivered by Christ and his apostles: and which she had held in the truth and purity of them, and is now exhorted to hold them fast, since this hour of temptation would be a trying time to her faith, patience, integrity, and constancy:
that no man take thy crown; not eternal happiness, called a crown of life, glory, and righteousness, and which was prepared for her, and promised to her, and would be certainly given her; nor was there any danger of another's taking it from her; not but that exhortations of this kind to the saints are necessary, with respect to that, to excite to diligence, care, and watchfulness; and are no ways contrary to their final perseverance, and certain salvation, but are means thereof: but either her honour for her faith and faithfulness, for her integrity, sincerity, and purity, is here meant; or the glorious things which were spoken of this church state, and to be accomplished in it, Psalm 87:3; see Isaiah 60:1.

Behold--omitted by the three oldest manuscripts and most ancient versions.
I come quickly--the great incentive to persevering faithfulness, and the consolation under present trials.
that . . . which thou hast--"The word of my patience," or "endurance" (Revelation 3:10), which He had just commended them for keeping, and which involved with it the attaining of the kingdom; this they would lose if they yielded to the temptation of exchanging consistency and suffering for compromise and ease.
that no man take thy crown--which otherwise thou wouldst receive: that no tempter cause thee to lose it: not that the tempter would thus secure it for himself (Colossians 2:18).

Thy crown - Which is ready for thee, if thou endure to the end.