Per ESPN.com's Tim MacMahon, Harden expressed his frustration after being called for four offensive fouls in the game:
"Scott Foster, man. I never really talk about officiating or anything like that, but just rude and arrogant. I mean, you aren't able to talk to him throughout the course of the game, and it's like, how do you build that relationship with officials? And it's not even that call [on the sixth foul]. It's just who he is on that floor.
"It's lingering, and it's something that has to be looked at for sure. For sure, it's personal. For sure. I don't think he should be able to even officiate our games anymore, honestly."
Paul also weighed in on Foster's officiating after he and Harden fouled out of the game in the fourth quarter.
"I don't know what else to do, know what I mean?" Paul said. "I met with the league with him before and all this stuff. I don't know what else to do."
Foster only called two fouls against Harden in the game, and Michael Smith called the reigning NBA MVP for a charge with one minute, 24 seconds remaining in the fourth quarter that led to his exit.
But Foster did call Harden for two offensive fouls, including a charge against LeBron James when he was driving to the basket late in the fourth quarter and Houston was trailing by two points.
The Rockets have had a contentious relationship with Foster dating back to last season. Paul told reporters after a win over the Portland Trail Blazers in January 2018 "there's history there" with Foster, and he sarcastically called the veteran official the man fans "pay to see."
In a 2016 survey conducted by Broderick Turner of the Los Angeles Times, Foster was voted the NBA's worst official by more than 30 players and coaches.
Harden and Paul had plenty of reasons to be frustrated, in addition to fouling out. Houston led by as many as 19 points in the third quarter before the Lakers went on a 51-27 run to close the game.