This fallen world is full of injustice, a reality the weak and vulnerable (e.g., slaves) experience too often (contra the principle reflected in texts as Exodus 22:21–22; Deuteronomy 24:14, Deuteronomy 24:17–18). It is precisely this reality that made being a slave so difficult. The term “suffer” is quite general, containing no indication as to the precise nature of the unjust penalty the master has imposed, whether imprisonment, a beating, even being sold or killed. (Masters in Peter’s day had the legal right to do any of these things.)
20 For what credit is it if, when you sin and are beaten for it, you endure? But if when you do good and suffer for it you endure, this is a gracious thing in the sight of God.