Luke 15:15-16

so he went and attached himself to a citizen of that land, who sent him to his fields to feed swine.

2 Peter 2:22

They verify the truth of the proverb: "The dog turns back to what he has vomited, the sow when washed will wallow 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
so he went and attached himself to a citizen of that land, who sent him to his fields to feed swine.
2 Peter 2:22
They verify the truth of the proverb: "The dog turns back to what he has vomited, the sow when washed will wallow in the mire."