Verse 3: (1 Tim. 6:20; 2 Tim. 1:13; Rev. 3:11) Remember therefore how thou hast received and heard, and hold fast, and (Rev. 3:19) repent. (Matt. 24:42, 43; 25:13; Mark 13:33; Luke 12:39, 40; 1 Thess. 5:2, 6; 2 Pet. 3:10; Rev. 16:15) If therefore thou shalt not watch, I will come on thee as a thief, and thou shalt not know what hour I will come upon thee.
[Keep in mind, etc., μνημόνευε] Again and again consider, as in Revelation 2:5 (Grotius).
[How, etc., πῶς εἴληφας καὶ ἤκουσας] That is, ἀκούων εἴληφας, hearing thou hast received. Λαμβάνειν, to take, or παραλαμβάνειν, to receive, לָקַח, to take, or קָבַל, to receive, is wont to be used of Doctrine, 1 Corinthians 11:23; 15:1, 3; Galatians 1:9; 1 Thessalonians 2:13; 4:1 (Grotius). How (that is, what things [Pareus, Beza), what doctrine [Grotius, similarly Zegers]: πῶς/how in the place of ποῖα, what things [Beza]: for it follows, and keep, namely, those things which thou hast received [certain interpreters is Glassius]: Thus Terence, Thus is man, in the place of, Such is man [Beza]: But it is best to retain the signification of the Adverb [Glassius’ “Grammar” 3:1:10:45]: how, that is, with what great ardor and joy [Durham]) thou hast received (that is, how thou didst undertake [Castalio, thus Ribera, Menochius, Glassius’ “Grammar” 3:1:10:45]: To receive is sometime taken for to undertake, or to learn [Glassius’ “Grammar” 3:1:10:45]) and heard (Montanus), namely, from the Apostles (Grotius, Tirinus): What conditions I set forth to you, and ye embraced (Durham).
Remember therefore how thou hast received and heard; to wit, from the apostles of the Lord Jesus Christ. All true reformation, either of doctrine or manners, lies in the reduction of it to the doctrine delivered, and the rules of life given by them.
[And, etc., καὶ τήρει] And keep (Erasmus, Piscator), or, observe (Beza, Grotius). Thus we have τηρεῖν, to keep, in John 14:15, 21, etc.; 15:10, 20, etc. (Grotius). Or, hold (Castalio), understanding those things (Beza, Piscator, Durham), the remaining things (Durham), those dying members (Drusius): or, those things, not certain things, but all (Grotius), that thou hast received (Drusius, similarly Castalio).
[Repent] Of those things of which thou art aware (Grotius): that is to say, Put off hypocrisy, sincerely supply service to the Church (Pareus).
And hold fast, and repent: wherein our judgment or practice is conformable to theirs, it is to be held fast; wherein it hath varied, it is to be repented of.
[If therefore thou shalt not watch] Keepers in the Temple kept watch even by night (Grotius).
[I will come, etc., ἥξω ἐπί σε—ποίαν ὥραν, etc.] In the place of κατὰ ποίαν ὥραν, at what hour: otherwise it is expressed ποίᾳ ὥρᾳ, Matthew 24:42 (Grotius). I will come to thee (or, upon thee [Piscator, Pareus], or, against thee [Beza], that is, for thy destruction [Beza]: Christ is said to come both when He will come unto universal Judgment, and at the time He carries off each one from this life: See John 21:22: ἐπί σε, on thee, is missing in a manuscript [Grotius]) as a thief (that is, unexpectedly [Tirinus]: But, just as the comparison with a thief is apt for the final Judgment, Matthew 24:43; 1 Thessalonians 5:2, so also for unexpected death, as here, and in other unexpected Judgments, as in Revelation 16:15: Now, this is spoke in a manner suitable to the matter, for sinners generally flatter themselves, thinking themselves to have sufficient time for repentance [Grotius]) and thou shalt not know at what hour, etc. (Montanus). It is epexegetical (Piscator). The sense: When thou wilt not at all imagine thou wilt die, and be called to the judgment (Ribera, Menochius).
If therefore thou shalt not watch, I will come on thee as a thief; if thou shalt not keep thyself free from gross sins or errors, and give diligence to do it, I will come to thee, not as a friend to comfort and refresh thee, but as a thief to rob and destroy thee, and that suddenly. And thou shalt not know what hour I will come upon thee; I will surprise thee with my judgments, and thou shalt not know when my judgments shall overtake thee.
 Greek: μνημόνευε οὖν πῶς εἴληφας καὶ ἤκουσας, καὶ τήρει, καὶ μετανόησον. ἐὰν οὖν μὴ γρηγορήσῃς, ἥξω ἐπί σε ὡς κλέπτης, καὶ οὐ μὴ γνῷς ποίαν ὥραν ἥξω ἐπί σε.  1 Corinthians 11:23: “For I have received (παρέλαβον) of the Lord that which also I delivered unto you, That the Lord Jesus the same night in which he was betrayed took bread…”  1 Corinthians 15:1: “Moreover, brethren, I declare unto you the gospel which I preached unto you, which also ye have received (παρελάβετε), and wherein ye stand…”  1 Corinthians 15:3: “For I delivered unto you first of all that which I also received (παρέλαβον), how that Christ died for our sins according to the scriptures…”  Galatians 1:9: “As we said before, so say I now again, If any man preach any other gospel unto you than that ye have received (παρελάβετε), let him be accursed.”  1 Thessalonians 2:13: “For this cause also thank we God without ceasing, because, receiving (παραλαβόντες) the word of God which ye heard of us, ye received it not as the word of men, but as it is in truth, the word of God, which effectually worketh also in you that believe.”  1 Thessalonians 4:1a: “Furthermore then we beseech you, brethren, and exhort you by the Lord Jesus, that as ye have received (παρελάβετε) of us how ye ought to walk and to please God…”  The Brothers 1:2.  See, for example, Psalm 134:1.  Matthew 24:42: “Watch therefore: for ye know not at what hour (ποίᾳ ὥρᾳ) your Lord doth come.”  Thus Codex Alexandrinus.