Proverbs 26:11

⁹ As a thorn goeth up into the hand of a drunkard, so is a parable in the mouth of fools.

¹⁰ The great God that formed all things both rewardeth the fool, and rewardeth transgressors.

As a dog returneth to his vomit, so a fool returneth to his folly.

¹² Seest thou a man wise in his own conceit? there is more hope of a fool than of him.

¹³ The slothful man saith, There is a lion in the way; a lion is in the streets.

Do read the surrounding verses too, because the context often says more than a single verse.

Compare

BSB: As a dog returns to its vomit, so a fool repeats his folly.
KJV: As a dog returneth to his vomit, so a fool returneth to his folly.
WEB: As a dog that returns to his vomit, so is a fool who repeats his folly.
ASV: As a dog that returneth to his vomit, [So is] a fool that repeateth his folly.
DARBY: As a dog turneth back to its vomit, [so] a fool repeateth his folly.
BLB: Like a dog returning to its vomit [is] a fool repeating his folly.

ÅB: Lik hunden som vender tilbake til sitt eget spy, er en dåre som kommer igjen med sin dårskap.
OTB: Som en hund vender tilbake til sitt spy, slik gjentar en dåre sin dårskap.
B1930: Lik hunden som vender tilbake til sitt eget spy, er en dåre som kommer igjen med sin dårskap.

2 Peter 2:22
But it is happened unto them according to the true proverb, The dog is turned to his own vomit again; and the sow that was washed to her wallowing in the mire.
Read in context
Matthew 12:45
Then goeth he, and taketh with himself seven other spirits more wicked than himself, and they enter in and dwell there: and the last state of that man is worse than the first. Even so shall it be also unto this wicked generation.
Read in context
Exodus 8:15
But when Pharaoh saw that there was respite, he hardened his heart, and hearkened not unto them; as the LORD had said.
Read in context