2 Peter 2:22

But the true proverb is verified in them, The dog hath returned to his own vomit; and the sow which was washed to its 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
and the rain descended, and the rivers rushed, and the winds blew, and set against that house, and it fell; and the fall of it was great.
Luke 14:30
saying, This man began to build, and was not able to finish.
Luke 17:32
Remember Lot's wife.
1 Timothy 5:15
For some are already turned aside after Satan.