Look to yourselves - This seems to be addressed to the lady to whom he wrote, and to her children. The idea is, that they should be particularly on their guard, and that their first care should be to secure their own hearts, so that they should not be exposed to the dangerous attacks of error. When error abounds in the world, our first duty is not to attack it and make war upon it; it is to look to the citadel of our own souls, and see that all is well guarded there. When an enemy invades a land, the first thing will not be to go out against him, regardless of our own strength, or of the security of our own fortresses, but it will be to see that our forts are well manned, and that we are secure there from his assaults. If that is so, we may then go forth with confidence to meet him on the open field. In relation to an error that is in the world, the first thing for a Christian to do is to take care of his own heart.
That we lose not those things which we have wrought - Margin: "Or, gained." Some copies read: "which ye have gained, but that ye." The reading here referred to in the margin is found in several manuscripts and also in the Vulgate, the Syriac, and the Aethiopic versions. It is not, however, adopted in the late critical editions of the New Testament, and the common reading is probably genuine. The sense is not materially varied, and the common reading is not unnatural. John was exhorting the family to whom this Epistle was written to take good heed to themselves while so many artful errorists were around them, lest they should be drawn away from the truth, and lose a part of the full reward which they might hope to receive in heaven. In doing this, nothing was more natural than that he, as a Christian friend, should group himself with them, and speak of himself as having the same need of caution, and express the feeling that he ought to strive also to obtain the full reward, thus showing that he was not disposed to address an exhortation to them which he was not willing to regard as applicable to himself.
The truth which is taught here is one of interest to all Christians - that it is possible for even genuine Christians, by suffering themselves to be led into error, or by failure in duty, to lose a part of the reward which they might have obtained. The crown which they will wear in heaven will be less bright than that which they might have worn, and the throne which they will occupy will be less elevated. The rewards of heaven will be in accordance with the services rendered to the Redeemer; and it would not be right that they who turn aside, or falter in their course, should have the same exalted honours which they might have received if they had devoted themselves to God with ever-increasing fidelity. It is painful to think how many there are who begin the Christian career with burnings zeal, as if they would strike for the highest rewards in heaven, but who soon waver in their course, and fall into some paralyzing error, until at last they receive, perhaps, not half the reward which they might have obtained.
But that we receive a full reward - Such as will be granted to a life uniformly consistent and faithful; all that God has to bestow on his people when most faithful and true. But who can estimate the "full reward" of heaven, the unspeakable glory of those who make it the grand business of their lives to obtain all they can of its bliss. And who is there that does not feel that he ought to strive for a crown in which not one gem shall be missing that might have sparkled there forever?

Look to yourselves - Be on your guard against these seducers; watch, pray, love God and each other, and walk in newness of life.
That we lose not those things which we have wrought - That we apostles, who have been the means of your conversion, may not be deprived of you as our crown of rejoicing in the day of the Lord Jesus.
Instead of the first person plural, απολεσωμεν, etc., We lose, etc., many MSS., versions, and fathers, read the whole clause in the second person plural, απολεσητε, Ye lose, etc. Take heed to yourselves that Ye lose not the things which Ye have wrought, but that Ye receive a full reward. This reading is more consistent and likely, and is supported by at least as good evidence as the other. We find that if these persons did not keep on their guard they might lose their salvation, and the apostles their rejoicing in the day of the Lord Jesus. Even this intimation might put them on their guard. Had the apostle said ye cannot finally fall, what a different effect would it have produced! Griesbach has placed these readings in the margin as being very probable.

(4) (e) Look to yourselves, that we lose not those things which we have wrought, but that we receive a full reward.
(4) He that makes shipwreck of doctrine, loses all.
(e) Beware, and take good heed.

Look to yourselves,.... This is an exhortation to the elect lady, and her children, to look about them, and take care of themselves, and beware of these deceivers, and their doctrines:
that we lose not those things which we have wrought; or as the Alexandrian copy, and many other copies, and the Vulgate Latin, Syriac, and Ethiopic versions read, "that ye lose not those things which ye have wrought"; in embracing the Gospel, making a profession of it, walking in it, showing a zeal, and contending for it, expressing a love both by words and actions to the ministers of it, and suffering much reproach on the account of it; all which would be lost, and in vain, should they at last drop the Gospel, and embrace the errors of the wicked; see Galatians 3:4. Moreover, such who do not go such lengths, as to let go the head, Christ, but retain him as the foundation, and the fundamental doctrines of the Gospel, yet, among many precious things, may lay much rubbish on this foundation; and therefore should take heed what they build upon it, since, though they themselves may be saved, their works may be destroyed, and so they suffer loss; see 1-Corinthians 3:11; and if we read the words, "that we lose not--which we have wrought"; the sense is the same, it being only a figure which rhetoricians call communion, and it is frequently used when a common duty is exhorted to; see 1-John 2:28; unless it should be thought that this has a peculiar reference to the ministers of the Gospel, as it may: for though the Gospel preached by them can never be lost, being the everlasting Gospel, and the word which abides for ever; yet it may be received in vain, and persons may fall from it, and imbibe error, and so the labour of Christ's faithful ministers may be so far in vain, and lost; and likewise, many souls whom they have thought they have gained to Christ, and that they have been instruments of working upon them for good, and have hoped they would be their joy and crown of rejoicing another day; when such are carried away by deceivers, fall off from the truth, ministers of the word lose what they thought they had wrought, which must give them great concern; and this is improved by the apostle into a reason and argument why the persons he wrote to should beware of seducers and their errors:
but that we receive a full reward; in heaven, and which itself is called the recompense of reward, and the reward of the inheritance; not that this is a reward of debt due to the works of men, which are not rewardable in themselves; for they are such as are due to God before they are performed; and when they are done, they are not profitable to him, nothing is given to him, or received by him; when all is done that can be done, men are unprofitable servants; but this is a reward of grace, God has of his own grace promised it to those who love and serve him; and because it will be given them of his grace, after their work is over, as wages are given to a servant when he has done his work, it goes by this name: and whereas it is said to be a "full" one, the meaning is not as if it was different to different persons, for there is but one recompense of reward, or reward of the inheritance common to all the saints; or, as if it might be incomplete in some; it only signifies a large and exceeding great reward; see Genesis 15:1; in which last place the same phrase is used as here; and where the Septuagint interpreters use the same words as here; and which is thus paraphrased by the Targumist,
"the Lord give thee a good recompence in this world for thy good work, and let thy reward be "full", or "perfect", in the world to come.''
And the Jews (g) often speak of a full reward, and an equal one, to be received hereafter. Perhaps regard is here had particularly to the ministers of the Gospel, who have their reward in part here, for the workman is worthy of his reward, and they will have it in full hereafter. Moreover, the apostle might here be concerned, that he, and every faithful minister, might have their full number, they expected, that none may be missing, and which he may call a full reward: though the above copies and versions read here, as before, "ye", and "not we".
(g) Targum on Eccl. i. 3. & ii. 11. & Midrash Kohelet, fol. 72. 4.

Look to yourselves--amidst the widespread prevalence of deception so many being led astray. So Christ's warning, Matthew 24:4-5, Matthew 24:24.
we lose not . . . we receive--The oldest manuscripts and versions read, "That YE lose not, but that YE receive."
which we have wrought--So one oldest manuscript reads. Other very old manuscripts, versions, and Fathers, read, "which YE have wrought." The we being seemingly the more difficult reading is less likely to have been a transcriber's alteration. Look that ye lose not the believing state of "truth and love," which WE (as God's workmen, 2-Corinthians 6:1; 2-Timothy 2:15) were the instruments of working in you.
a full reward--of grace not of debt. Fully consummated glory. If "which YE have wrought" be read with very old authorities, the reward meant is that of their "work (of faith) and labor of love." There are degrees of heavenly reward proportioned to the degrees of capability of receiving heavenly blessedness. Each vessel of glory hanging on Jesus shall be fully happy. But the larger the vessel, the greater will be its capacity for receiving heavenly bliss. He who with one pound made ten, received authority over ten cities. He who made five pounds received five cities; each according to his capacity of rule, and in proportion to his faithfulness. Compare 1-Corinthians 15:41. "There is no half reward of the saints. It is either lost altogether, or received in full; in full communion with God" [BENGEL]. Still no service of minister or people shall fail to receive its reward.

That we lose not the things which we have wrought - Which every apostate does. But receive a full reward - Having fully employed all our talents to the glory of him that gave them. Here again the apostle modestly transfers it to himself.