Albert Barnes on Revelation 3:11

Behold, I come quickly. That is, in the trials referred to. Rev 1:1, Revv 1:11, Rev 1:16.

Hold that fast which thou hast. That is, whatever of truth and piety you now possess. Rev 3:3.

That no man take thy crown. The crown of life appointed for all who are true believers. 2Ti 4:8. The truth which is taught here 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 for ever. 2Jn 8.

(a) "come" Zeph 1:14 (b) "quickly" Rev 3:3