13 But we will not boast of things without our measure, but according to the measure of the rule  which God hath distributed to us, a measure to reach even unto you.
13 We, however, will not boast beyond proper limits, but will confine our boasting to the sphere of service God himself has assigned to us, a sphere that also includes you.
13 But we will not boast beyond limits, but will boast only with regard to the area of influence God assigned to us, to reach even to you.
13 We aren't making outrageous claims here. We're sticking to the limits of what God has set for us. But there can be no question that those limits reach to and include you.
13 We, however, will not boast beyond measure, but within the limits of the sphere which God appointed us--a sphere which especially includes you.
13 We will not boast about things done outside our area of authority. We will boast only about what has happened within the boundaries of the work God has given us, which includes our working with you.
Matthew Henry's Commentary on 2 Corinthians 10:13
Commentary on 2 Corinthians 10:12-18
(Read 2 Corinthians 10:12-18)
If we would compare ourselves with others who excel us, this would be a good method to keep us humble. The apostle fixes a good rule for his conduct; namely, not to boast of things without his measure, which was the measure God had distributed to him. There is not a more fruitful source of error, than to judge of persons and opinions by our own prejudices. How common is it for persons to judge of their own religious character, by the opinions and maxims of the world around them! But how different is the rule of God's word! And of all flattery, self-flattery is the worst. Therefore, instead of praising ourselves, we should strive to approve ourselves to God. In a word, let us glory in the Lord our salvation, and in all other things only as evidences of his love, or means of promoting his glory. Instead of praising ourselves, or seeking the praise of men, let us desire that honour which cometh from God only.