As a dog returneth to his vomit
Who being sick with what he has eaten, casts it up again, and afterwards returns unto it and licks it up; [so] a fool returneth to his folly,
or "repeats" F1 it, time after time, many times, as Ben Melech; or a wicked man turns to his wickedness, who, having had some qualms upon his conscience for sin, for a while forsakes it; but that fit being over, and he forgetting all his former horror and uneasiness, returns to his old course of life: a wicked man is here compared to a dog, as he is elsewhere for his impudence and voraciousness in sinning; and the filthiness of sin is expressed by the vomit of a dog, than which nothing is more nauseous and loathsome; and the apostasy of the sinner, from an external course of righteousness into open profaneness is signified by the return of this creature to it. This is said to be a "true proverb", ( 2 Peter 2:22 ) , where it is quoted and applied.
F1 (hnwv) "qui iterat", Tigurine version, Michaelis; "iterans", Montanus, Mercerus, Cocceius, Gejerus; "duplicans", Schultens.