Like a dog that returns to his vomit is a fool who repeats his folly.
See here, 1. What an abominable thing sin is, and how hateful sometimes it is made to appear, even to the sinner himself. When his conscience is convinced, or he feels smart from his sin, he is sick of it, and vomits it up; he seems then to detest it and to be willing to part with it.
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" (a) 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...
returneth . . . folly--Though disgusting to others, the fool delights in his folly.