Luke 15:15-16

And he went and attached himself to one of the citizens of that country, who sent him into his fields to feed swine.

2 Peter 2:22

But it has happened to them according to the true proverb: The dog has turned again to his own vomit; and, The sow that was washed, to her wallowing in the mire.

Treasury of Scripture Knowledge

Summary

And the swine, because it divideth the hoof, yet cheweth not the cud, it is unclean unto you: ye shall not eat of their flesh, nor touch their dead carcase.

Bible References

The swine

Luke 15:15
And he went and attached himself to one of the citizens of that country, who sent him into his fields to feed swine.
2 Peter 2:22
But it has happened to them according to the true proverb: The dog has turned again to his own vomit; and, The sow that was washed, to her wallowing in the mire.