A string of MPs for West Yorkshire condemned the Prime Minister after Jo Cox's name was brought into debate in the Commons.
Boris Johnson told Parliament on Wednesday evening that the "best way" of honouring murdered Batley & Spen MP would be by "getting Brexit done".
The comment was made after MP Paula Sherriff, who represents neighbouring constituency Dewsbury, pleaded with the Prime Minister to stop using divisive language as MPs reconvened following Tuesday's court ruling that the decision to prorogue Parliament was 'unlawful'.
Ms Sherriff criticised Mr Johnson's repeated use of "surrender act" while describing legislation which prevented ministers forcing through a no-deal Brexit, to which the Prime Minister replied he had "never heard so much humbug".
She said: "I genuinely do not seek to stifle robust debate but this evening the Prime Minister has continually used pejorative language to describe an Act of Parliament passed by this House and I'm sure that you would agree Mr Speaker that we should not resort to using offensive, dangerous or inflammatory language about legislation we do not like."
Referring to a plaque commemorating Jo Cox, Ms Sherriff added: "We stand here, Mr Speaker, under the shield of our departed friend with many of us in this place subject to death threats and abuse every single day and let me tell the Prime Minister that they often quote his words, surrender act, betrayal, traitor, and I for one am sick of it.
"We must moderate our language and it has to come from the Prime Minister first, so I would be interested in hearing his opinion he should be absolutely ashamed of himself."
Mr Johnson replied: "I think Mr Speaker...I have never heard so much humbug in my life", before adding, "what I will say is that the best way to honour the memory of Jo Cox and indeed the best to bring this country together would be, I think, to get Brexit done."
The comment provoked gasps in the chamber, before later criticism from fellow West Yorkshire MPs, as well as Mrs Cox's widower Brendan Cox.
Leeds West MP Rachel Reeves said: "Appalled by the Prime Minister this evening. He breaks the law and uses dangerous language that stokes division and worse in our communities."
Castleford and Pontefract MP Yvette Cooper said: "The language Boris Johnson uses is designed deliberately to escalate tension, division and hatred."
Brendan Cox added he felt "a bit sick" after seeing the dialogue.
In a tweet, he wrote: "The best way to honour Jo is for all of us (no matter our views) to stand up for what we believe in, passionately and with determination. But never to demonise the other side and always hold onto what we have in common."