A humble messenger of God is willing to seek only The Lord’s Glory
But he who boasts is to boast in the Lord. (10:17)
This essential truth, found throughout Scripture, is a stinging rebuke to all self-glorying false teachers. In Psalm 20:7 David wrote, “Some boast in chariots and some in horses, but we will boast in the name of the Lord, our God,” while in Psalm 34:2 he added, “My soul shall make its boast in the Lord; the humble shall hear it and rejoice.” Through the prophet Jeremiah God declared,
Thus says the Lord, “Let not a wise man boast of his wisdom, and let not the mighty man boast of his might, let not a rich man boast of his riches; but let him who boasts boast of this, that he understands and knows Me, that I am the Lord who exercises lovingkindness, justice and righteousness on earth; for I delight in these things,” declares the Lord. (Jer. 9:23–24)
Paul had the above passage in mind when he wrote this verse, and also when he wrote earlier to the Corinthians, “Just as it is written, ‘Let him who boasts, boast in the Lord’ ” (1 Cor. 1:31). To the Romans he wrote, “Therefore in Christ Jesus I have found reason for boasting in things pertaining to God. For I will not presume to speak of anything except what Christ has accomplished through me, resulting in the obedience of the Gentiles by word and deed” (Rom. 15:17–18). He vowed in Galatians 6:14, “But may it never be that I would boast, except in the cross of our Lord Jesus Christ, through which the world has been crucified to me, and I to the world.”
After Martin Luther’s death, his friends found a scrap of paper in his pocket on which the great Reformer had written, “We are all beggars.” Humble men of God realize that they have nothing to boast about. If they preach the gospel, it is because God’s Word is a fire in their bones (Jer. 20:9) and they are compelled to preach (1 Cor. 9:16). They serve the church only because Christ puts them into service (1 Tim. 1:12), and any success they have is attributable solely to the grace of God at work in them (1 Cor. 15:10). They cry out with the psalmist, “Not to us, O Lord, not to us, but to Your name give glory” (Ps. 115:1).
MacArthur New Testament Commentary
17 As in 1 Corinthians 1:31, Paul cites Jeremiah 9:24 (9:23 [LXX]). The contrast in Jeremiah 9:23–24 (9:22–23 [LXX]) is between proper and improper boasting, between boasting of one’s own wisdom, strength, and riches as though these were derived from oneself, and boasting “about this: understanding and knowing that I am the Lord who exercises mercy, judgment, and righteousness on the earth, for my pleasure resides in these” (Jer 9:23 [LXX]). Against this OT background, boasting “in the Lord” is boasting about the character and deeds of the Lord. Other boasting is illegitimate, whether it be of one’s own accomplishments or status (1 Co 1:26–31) or of another person’s achievements as though they were one’s own (v. 16). For Christians, only boasting “in the Lord” is legitimate—boasting of who Jesus Christ is and what he has done for them (Gal 6:14) or through them (Ro 15:18; cf. Ac 14:27) or can do through them. Here Paul is confident the Lord will make his work in Rome and Spain fruitful.
The Expositor’s Bible Commentary