12 For we dare not make ourselves of the number, or compare ourselves with some that commend themselves: but they measuring themselves by themselves, and comparing themselves among themselves, are not wise.
People who commend themselves are those who wish to dominate, claiming authority for their own name. A person who is sent on a mission lays claim to power, not on his own behalf but on behalf of the one who sent him. Here Paul is saying that he has been chosen as a steward of the Lord. By not presuming to anything beyond what has been granted to him, he is not associating himself with those who preach without a commission. Commentary on Paul’s Epistles.
"For we are not bold to number, or compare in ourselves with some that commend themselves."
Here he both shows that those false Apostles are boasters and say great things of themselves: and ridicules them as commending themselves. 'But we do no such thing: but even if we shall do anything great, we refer all unto God, and compare ourselves with one another.' Wherefore also he added,
"But they themselves measuring themselves by themselves and comparing themselves among themselves are without understanding." Now what he says is this: 'we do not compare ourselves with them, but with one another.' For further on he says, "in nothing am I behind the very chiefest Apostles;" [2 Corinthians 12:11] and in the former Epistle, "I labored more abundantly than they all;" [1 Corinthians 15:10] and again, "Truly the signs of an Apostle were wrought among you in all patience." [2 Corinthians 12:12] 'So that we compare ourselves with ourselves, not with those that have nothing: for such arrogance comes of folly.' Either then he says this with reference to himself, or with reference to them, that 'we dare not compare ourselves with those who contend with one another and boast great things and do not understand:' that is, do not perceive how ridiculous they are in being thus arrogant, and in exalting themselves among one another.
The fundamental fallacy of these men, who prefer to walk in roundabout error than keep to the straight path of truth, is that they have nothing but their own tiny, changing, human minds to measure the divine mind, infinitely capacious and utterly immutable, a mind that can count uncountable things without passing from one to the next. Such men, to use the words of the apostle, “comparing themselves with themselves,” end by understanding nothing. Of course, every time such philosophers decide to do something, they have to form a new mental resolution because their minds are mutable, and they imagine it is the same with God. Without having a notion of God, they mistake themselves for him, and instead of measuring God by God, they compare themselves to themselves.
As often as you think of the perfection of the virtues, do not consider what others have less than you have but what you have less than you ought to have. You should not think that you are perfect in virtue if you see other women given over to sins; nor consequently should you credit yourself with any greater speed if you see some women either backsliding or walking feebly. Nor, therefore, must one with watery eyes be proclaimed to have healthy eyes because a blind man seems thoroughly closed off from the light, nor must someone be declared healthy who lies half-dead with a serious wound, if another is found dead because of a more serious wound. Nor must anyone lay claim to glory as a victor who, although not killed by the enemy, still is being held captive by the enemy. Therefore, do not compare yourself to others but to yourself. Hear the apostle doing this and salutarily warning us to do the same. For, writing to the Corinthians, he says, “Not that we dare to class or compare ourselves with some of those who recommend themselves. But when they measure themselves by one another and compare themselves with one another, they are without understanding.”
[AD 215] Clement of Alexandria on 2 Corinthians 10:12