See here, 1. Saints secured from ruin. Those that are upright in their way, that mean honestly in all their actions, adhere conscientiously to the sacred and eternal rules of equity, and deal sincerely both with God and man, their integrity will keep them from the temptations of Satan, which shall not prevail over them, the reproaches and injuries of evil men, which shall not fasten upon them, to do them any real mischief, Psa 25:21.
Hic murus aheneus esto, nil conscire sibi.
Be this thy brazen bulwark of defence,
Still to preserve thy conscious innocence.
2. Sinners secured for ruin. Those that are wicked, even their wickedness will be their overthrow at last, and they are held in the cords of it in the mean time. Are they corrected, destroyed? It is their own wickedness that corrects them, that destroys them; they alone shall bear it.

Righteousness keepeth him that is upright in the way,.... Men of uprightness and integrity, whose hearts are sincere in the ways of God; the principle of grace and righteousness in them keeps them in those ways, and will not suffer them to turn aside into crooked paths; the word of righteousness, the doctrine of the Gospel, is a means of preserving them from sin, and of keeping them in the right way; particularly the doctrine of Christ's righteousness, and justification by it, is a great antidote against sin, and a powerful motive and incentive to the performance of good works, and all the duties of religion: it engages men to observe every command of Christ, to walk in all his ways; and is a great preservative from false doctrine and antichristian worship;

but wickedness overthroweth the sinner; it is the cause of his utter overthrow, of his being punished with everlasting destruction. It is, in the Hebrew text, "sin" (b) itself; the sinner is so called, because he is perfectly wicked, as Jarchi observes; he is nothing but sin, a mere mass of sin and corruption. Aben Ezra renders it, "the man of sin"; and it may be well applied to him, who is emphatically called so, and is likewise the son of perdition; who, for his wickedness, will be overthrown and destroyed at the coming of Christ, and with the brightness of it, Th2 2:3.

(b) "peccatum"; Montanus, Vatablus, Cocceius, Michaelis; "lapsationem", Schultens.

A sentiment of frequent recurrence, that piety benefits and sin injures.