The apostle in these verses attests their integrity by the sincerity of their conversation. This he does not in a way of boasting and vain-glory, but as one good reason for desiring the help of prayer, as well as for the more comfortably trusting in God (Heb 13:18), and for the necessary vindication of himself from the aspersions of some persons at Corinth, who reproached his person and questioned his apostleship. Here,

I.He appeals to the testimony of conscience with rejoicing (Co2 1:12), in which observe, 1. The witness appealed to, namely, conscience, which is instead of a thousand witnesses. This God's deputy in the soul, and the voice of conscience is the voice of God. They rejoiced in the testimony of conscience, when their enemies reproached them, and were enraged against them. Note, The testimony of conscience for us, if that be right and upon good grounds, will be matter of rejoicing at all times and in all conditions. 2. The testimony this witness gave. And here take notice, Conscience witnessed, (1.) Concerning their conversation, their constant course and tenour of life: by that we may judge of ourselves, and not by this or that single act. (2.) Concerning the nature or manner of their conversation; that it was in simplicity and godly sincerity. This blessed apostle was a true Israelite, a man of plain dealing; you might know where to have him. He was not a man who seemed to be one thing and was another, but a man of sincerity. (3.) Concerning the principle they acted from in all their conversation, both in the world and towards these Corinthians; and that was not fleshly wisdom, nor carnal politics and worldly views, but it was the grace of God, a vital gracious principle in their hearts, that cometh from God, and tendeth to God. Then will our conversation be well ordered when we live and act under the influence and command of such a gracious principle in the heart.

II.He appeals to the knowledge of the Corinthians with hope and confidence, Co2 1:13, Co2 1:14. Their conversation did in part fall under the observation of the Corinthians; and these knew how they behaved themselves, how holily, and justly, and unblamably; they never found any thing in them unbecoming an honest man. This they had acknowledged in part already, and he doubted not but they would still do so to the end, that is, that they would never have any good reason to think or say otherwise of him, but that he was an honest man. And so there would be mutual rejoicing in one another. We are your rejoicing, even as you also are ours in the day of the Lord Jesus. Note, It is happy when ministers and people do rejoice in each other here; and this joy will be complete in that day when the great Shepherd of the sheep shall appear.

Have acknowledged us in part - Απο μερους may signify here not in part, but some of you; and it is evident, from the distracted state of the Corinthians, and the opposition raised there against the apostle, that it was only a part of them that did acknowledge him, and receive and profit by his epistles and advice.

We are your rejoicing, etc. - You boast of us as the ministers of Christ through whom ye have believed; as we boast of you as genuine converts to the Christian faith, and worthy members of the Church of God.

As also you have acknowledged us in part,.... This may refer either to the thing known and acknowledged, namely, the integrity of the apostle's conversation, and others; which though they did not know thoroughly and perfectly, yet did in part, and that so far as that they might acquit them from the charge brought against them; or to the persons who knew this, as that there were some in the church of Corinth, a part of them, though not all, who knew and had acknowledged them to be upright and sincere ministers of the word, and had declared that they had reason to rejoice and bless God that ever they heard them: and

that we are your rejoicing: or "glorying in", or "unto the day of the Lord Jesus": when he shall come to judge the world in righteousness, then they should before him, angels and men, rejoice and glory in this, that they had been blessed with such sincere and faithful ministers, who sought not any worldly advantage, but the glory of Christ, and the salvation of souls:

even as, adds the apostle,

ye also are ours; we do now, and so we shall then, rejoice and glory in this, that our labour among you was not in vain, but was blessed for your conversion and edification.

in part--In contrast to "even to the end": the testimony of his life was not yet completed [THEOPHYLACT and BENGEL]. Rather, "in part," that is, some of you, not all [GROTIUS, ALFORD]. So in Co2 2:5; Rom 11:25. The majority at Corinth had shown a willing compliance with Paul's directions in the first Epistle: but some were still refractory. Hence arises the difference of tone in different parts of this Epistle. See Introduction.

your rejoicing--your subject of glorying or boast. "Are" (not merely shall be) implies the present recognition of one another as a subject of mutual glorying: that glorying being about to be realized in its fulness "in the day (of the coming) of the Lord Jesus."