The incident occurred Wednesday in a bakery in the heavily Jewish neighborhood of Borough Park in Brooklyn, CNN reported. Weiner, like his antagonist, Saul Kessler, is a Jew.
"You're a real scumbag," Kessler yelled, starting the slanging match.
When Weiner retorted, "Very nice, that's a charming guy right there," Kessler came back with "Married to an Arab."
Weiner's wife, Huma Abedin, is not, in fact, an Arab. Her father was an Islamic scholar from India, and her mother was born in Pakistan. Abedin, a U.S. citizen, works for former Secretary of State Hillary Clinton.
Kessler later told CNN he should not have called Weiner a "scumbag." But he stood by his Arab remark, suggesting that a Jew marrying an Arab is "like a betrayal."
"It's just a certain feeling I have as a Jew," Kessler said. "And my attitude is that -- not all Arabs -- but, in general, ... they want to kill every Jew."
Weiner, hit hard by revelations that he was involved in sexting even after resigning from Congress over an earlier sexting scandal, is trailing in the polls for next week's Democratic primary.