Jamieson, Fausset and Brown on Isaiah 57:2

2. Or, "he entereth into peace"; in contrast to the persecutions which he suffered in this world (Job 3:13, 17). The Margin not so well translates, "he shall go in peace" (Psa 37:37; Lu 2:29).

rest--the calm rest of their bodies in their graves (called "beds," 2Ch 16:14; compare Is 14:18; because they "sleep" in them, with the certainty of awakening at the resurrection, 1Th 4:14) is the emblem of the eternal "rest" (He 4:9; Re 14:13).

each one walking in ... uprightness--This clause defines the character of those who at death "rest in their beds," namely, all who walk uprightly.