Painting mystery...

[Dr. Bombay]

There is a painting in an episode of Bewitched of a nobleman sitting on a horse and a peasant that is standing near the horse. I've heard it is a real painting but I can't find anything about it. Here's a picture of it http://home.earthlink.net/~e-bob/bw/229-horseman.jpg.

I was hoping maybe one of you could tell me what it's called and who the artist is.