During a social media storm against Rob Kardashian's former fiancee, Blac Chyna, he also made a comment about Caitlyn Jenner and his mother, Kris Jenner.
In the tweet, which has since been deleted, Rob revealed that Kris had told him to stop his Twitter rant against Chyna, who is the mother of his daughter, Dream Kardashian, reports The Inquisitr.
"My mom keeps telling me to stop," wrote Rob, "but she was married to a dude named Caitlyn, so I'm def not listening to her."
Caitlyn's son, Brody Jenner, was reported be upset about the comment, according to Radar Online.
"Brody's never liked Rob, who he sees as a screwed-up punk who's all mouth and no class," said an insider.
"He's like, 'How dare he attack Caitlyn, after everything she's done for him?'" the source added. "The whole dig towards his mom for marrying Bruce was revolting and way out of line."
Now, Brody is reportedly prepared to fight Rob over the tweet.
"[Rob's] had this coming for a while, with all the sneering and rude comments since Caitlyn announced her transition," said the insider. "But this public attack has crossed the line."
Earlier in July, Instagram shut down Rob's page after he posted nude images of Chyna, TMZ reports. Rob posted naked photos of Chyna, along with texts from her and those whom she had allegedly cheated on him with.
After Instagram shut him down for the images, Rob told his followers to "peep my Twitter," where he posted the same nude photos of Chyna.
"Just sad," tweeted Rob. "Loved Chyna as my wife and accepted all the wrong she did and continued to ride for her and remain loyal to her. Never did I cheat."
"But she couldn't remain loyal and cheated and f***ed way too many people and she got caught and now this is all happening and it's sad," said Rob in another tweet.
Twitter eventually removed the nudes, as well.
Caitlyn and Rob have not been as close as they once were since Caitlyn's transition, an insider said in 2016, according to Radar Online.
However, the source added at the time that Rob and Caitlyn "do not have any bad blood with each other. It's not like that at all."
"Even though Caitlyn is not technically Dream’s grandmother, she definitely wants to meet Dream," said the insider. "Of course, Caitlyn has sent Rob and Blac a baby gift."
"But Caitlyn just seems to feel that the best time for the meeting isn’t now," added the source. "She says she wants to wait, at least, until the new family is all settled in."