ISB ~ 2 Peter 2 v22

the true proverb:The first saying comes from Prov 26:11, and the second is a variation on a familiar maxim from the Hellenistic world. In this context, the point of both is that sinners once saved can again become defiled in sin. Jewish tradition disliked dogs and swine as filthy and objectionable animals (Ex 22:31; Lev 11:7; Mt 7:6).