2Thess 3:4

“Confidence in the Lord touching you, brethren, that ye both do and will do the things which we command you."”

“After the apostle prayed for the Thessalonians and said: God is faithful and will certainly complete the work of salvation begun in you, but lest you think that everything depends only on God and therefore give yourselves over to laziness, he now requires cooperation on their part as well, as if saying: God is faithful and will undoubtedly fulfill His work, but on the condition that you also labor. Notice the wisdom of the apostle. He did not simply say: "we are confident about you," but "in the Lord," that is, we trust in the loving-kindness of God, that it will fill you with strength, in order to show them that everything depends on God. And he did not simply say: "we are confident in the Lord," but: "about you," and: "you do and will do," so that they, attributing everything to God, would not become lazy. One must entrust everything to God, but in such a way as to act oneself as well. He was not satisfied to say: "you do," but added: "you will do," showing that we must be zealous for virtue until our very last breath.”

“Second, on their side he says "and we have confidence concerning you," brothers, namely based on the grace you have received, but "in the Lord," not in your own strength. "We have confidence in you, beloved, of things better and nearer to salvation" (Heb 6:9). "That the things which we command, you both do and will do," i.e., that you will persevere. "All the words that the Lord has spoken we will do" (Exod 24:7).”

“But we trust in the Lord concerning you, that you both do and will do the things which we command. In order that he may deserve to be entrusted with the entire defense of God, he does not doubt that those things which he commanded them in the name of the Lord will be done by them and will come to pass.”