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” (Rev 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 (Col 2:18).