2 Corinthians 7:10

worketh . . . worketh--In the best Greek reading the translation is, "worketh (simply) . . . worketh out." "Sorrow" is not repentance, but, where it is "godly," "worketh" it; that is, contributes or tends to it (the same Greek word is in Rom 13:10). The "sorrow of the world" (that is, such as is felt by the worldly) "worketh out," as its result at last, (eternal) death (the same Greek verb is in Co2 4:17; also see on Co2 4:17). repentance . . . not to be repented of--There is not in the Greek this play on words, so that the word qualified is not "repentance" merely, but "repentance unto salvation"; this, he says, none will ever regret, however attended with "sorrow" at the time. "Repentance" implies a coming to a right mind; "regret" implies merely uneasiness of feeling at the past or present, and is applied even to the remorse of Judas (Mat 27:3; Greek, "stricken with remorse," not as English Version, "repented himself"); so that, though always accompanying repentance, it is not always accompanied by repentance. "Repentance" removes the impediments in the way of "salvation" (to which "death," namely, of the soul, is opposed). "The sorrow of the world" is not at the sin itself, but at its penal consequences: so that the tears of pain are no sooner dried up, than the pleasures of ungodliness are renewed. So Pharaoh, Exo 9:27-30; and Saul, Sa1 15:23-30. Compare Isa 9:13; Rev 16:10-11.

— Jamieson-Fausset-Brown Commentary (public domain)