"Dave" wrote
That's one of those expressions that truly highlights cultural differences.
Most Jews I know, including my wife, think it most odd that haggling over
price offends Wasp sensibilities. Conversely, a lot of the folks using the
term "Jewing him down" likely never met a Jew in their lives.

It's biblical and at the root of both faiths, as well as a fine joke.

Abraham is lazying in his tent in the noon heat when who should come hiking
across the desert but God himself. Abie quickly invites him in for a veal
sandwich and inquires his destination. "To Sodom and Gomarrah to check out
rumors that the people there are disobeying me, and it that's true to smite
them!" "Oy!" thinks Abie "My slums" and asks God if he would spare his slums
for 50 good souls. God agrees, but Abie knows he can't find 50 so he proceeds to
"jew" God down from 50 to 5 IIRC. But then he can't even produce the 5!

God tells Abie that he really likes him and plans to give him and his
descendents all the land between the two great rivers (most of what's now Iraq)
..... but Abie needs a badge or mark to show that he is God's favorite. Then God
has Abie cut off the end of his penis - and all his sons penises, and so on.
And to this day .....

Thus the perchance for God's chosen People to bargain. It's an integral part of
their beliefs.