Rea was acquired Friday in a seven-player trade with the Padres that also sent right-hander Andrew Cashner to Miami. The Marlins are keeping Cashner and sending Rea back in a new deal.
The Marlins get pitching prospect Luis Castillo back, who was in the original deal for Rea. Castillo, a 23-year-old right-hander, was 7-3 with a 2.25 ERA in 100 innings pitched for Jupiter, the Marlins' Class-A team in the Florida State League at the time of Friday's trade.
Rea was placed on the 15-day disabled list with a right elbow sprain on Sunday.
Rea pitched 3⅓ scoreless innings and allowed one hit against the St. Louis Cardinals before he left Saturday's game. He said he first felt pain warming up before the game.
Information from The Associated Press was used in this report.