Isaiah 42:21
21. his righteousness—not His people's, but His own; Isa 42:24 shows that they had no righteousness (Isa 45:24; 59:16). God is well pleased with His Son ("in whom My soul delighteth," Isa 42:1), "who fulfils all righteousness" (Mt 3:15) for them, and with them for His sake (compare Isa 42:6; Ps 71:16, 19; Mt 5:17; Ro 10:3, 4; Php 3:9). Perhaps in God's "righteousness" here is included His faithfulness to His promises given to Israel's forefathers [ROSENMULLER]; because of this He is well pleased with Israel, even though displeased with their sin, which He here reproves; but that promise could only be based on the righteousness of Messiah, the promised seed, which is God's righteousness.
Isaiah 45:24
24. Rather, "Only in Jehovah shall men say of me (this clause is parenthetical), is there righteousness" (which includes salvation, Isa 45:21, "a just God and a Saviour," Isa 46:13), &c. [MAURER].
strength—namely, to save. shall men come—Those who have set themselves up against God shall come to Him in penitence for the past (Isa 19:22). ashamed— (Isa 45:16; Isa 54:17; 41:11).