Bede, on Prov 26:11

“As a dog that returneth to his vomit, so is the fool that repeateth his folly.”

“As a dog returns to his vomit, etc. When a dog vomits, he surely ejects the food that was weighing down his chest; but when he returns to his vomit, he is again burdened by what had relieved him; and those who lament their sins, surely confess and cast out the wickedness which was badly satisfying them and which was weighing down the innermost parts of their mind, which, after confession, they resume while they long for it.”

Imported from an open dataset — not yet checked against the printed edition.