As Michael Gehlken of the Dallas Morning News noted, Prescott pulled himself from that practice and is glad he did so.
"I've never felt anything in my arm, so that was the first alarm that went off," Prescott said.
The MRI is scheduled to happen after the team returns home to Dallas from their training camp headquarters in Oxnard, California.
Prescott also said he's hoping to take part in team drills on Monday and participate in the Cowboys' third exhibition matchup, which is Saturday, Aug. 21 at home against the Houston Texans. Beforehand, Dallas is set to play at the Arizona Cardinals on Friday.
Any setback to Prescott is going to cause concern considering he is the franchise quarterback who suffered a season-ending ankle injury that required surgery last year.
Dallas exercised caution with the 28-year-old during offseason practices and surely needs him under center to reach its full potential.
Prescott entered the 2021 offseason as a two-time Pro Bowler with four seasons of more than 3,300 passing yards on his resume.
Right now, it appears this injury won't hinder Prescott's ability to suit up for the team's regular-season opener on Sept. 9 at the Tampa Bay Buccaneers.
If Prescott is sidelined following this setback, however, Garrett Gilbert is listed as the next man up on the unofficial quarterback depth chart. Ben DiNucci and Cooper Rush sit behind him in that order.