Bede — on 1Pet 3:18 (Commentary on the Catholic Epistles)

“Because Christ also once died for our sins, etc. Therefore, the righteous one who suffers imitates Christ; the one corrected by scourging imitates the thief who recognized Christ on the cross and entered paradise with Christ from the cross; the one who does not desist from faults even amid scourging imitates the left-hand thief, who ascended the cross for his sins and after the cross fell into Tartarus. But he recalls that Christ died once, so that it might also remind us that an eternal reward is given for our temporary sufferings.”