Rob Kardashian was MIA during last night's ESPY Awards.

Rob Kardashian 'Furious' With Kim's Rolling Stone Comments About His Weight, Drug Use

Although Caitlyn Jenner, his former step-father, was honored at the event with the Arthur Ashe Courage Awards, Kardashian opted to spend the evening at home with his three-year-old niece, Penelope, daughter of his oldest sister Kourtney and her now ex-boyfriend, Scott Disick.

"Caitlyn Jenner had the support of Kim Kardashian, Brody Jenner, and seven of her other children when she accepted the Arthur Ashe Courage Award at the July 15 ESPYS, but there was one very familiar face missing from the crowd: Jenner's former stepson, Rob Kardashian," Us Weekly reported on Thursday. "While his siblings joined Jenner, 65, at the ceremony, the reclusive sock designer, 28, opted out -- but still kept his family top of mind."

Rob Kardashian Responds To Kourtney Kardashian & Scott Disick's Split?

As previously reported, Kardashian is said to be irate over his sister's recent breakup with Disick.

Following photos of Disick and his ex-girlfriend, Chloe Bartoli, a source told Radar Online that Kardashian was having violent thoughts about Penelope's father.

“Rob is really hurt by this entire situation," the source explained. “Scott was one of the only people that Rob could really turn to that understood what he was going through. Rob just cannot believe that Scott did this to his sister and her family and he says he really wants to knock Scott the f**k out. Scott has tried to reach out to Rob and get information out of him but Rob is not going to have any contact with him."

Keeping Up With The Kardashians season 10 airs Sundays on the E! Network at 9 p.m.

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Rob kardashian, Keeping Up With The Kardashians, E!, Reality TV, Espy awards, Caitlyn jenner