2 Peter 2:22

but the proverb is exactly verified in them, "the dog is return'd to his own vomit: the sow that was wash'd, is wallowing in the mire."

Treasury of Scripture Knowledge

Summary

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.

Bible References

General references

Matthew 7:27
the rain descends, the flood rushes on, the winds blow, and beat upon the house: down it falls, and wide are its ruins.
Luke 14:30
this man, will they say, began to build, but wanted stock to finish.
Luke 17:32
remember Lot's wife.
1 Timothy 5:15
for some have already revolted to paganism.