New York Supreme Court Justice Arthur Engoron threatened to gag Donald Trump's attorneys after one of them referred to his law clerk.

"Do not refer to my staff again," the judge said, according to The Messenger reporter Adam Klasfeld, who is in the courtroom.

"[Trump attorney Chris Kise] refers to his principal law clerk, and now Engoron, while calm, is furious, noting that the obsession with his clerk seems misogynistic to him," MSNBC legal analyst Lisa Rubin reported.

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Henry Rosoff called it a "heated back and forth."

Trump attorney Alina Habba sought to assure the judge that Kise's objections were not because of misogyny.

"I assure you that's not the issue," she said.

The Trump team had contended that the clerk, who Trump has referred to in the past as "partisan," spread bias to the judge. Engoron, however, warned that he would extend Trump's gag order to them if they continued to reference his staff.

"If there's any further reference to anyone on my staff … I will consider expanding the gag order to include the attorneys, to include yourself," Engoron remarked.