Verses 4 through 8 speak of Jehovah's righteousness and salvation for Israel.
First, Jehovah tells His people to hearken to Him. "Hearken to Me, O My people;/Give ear to Me, O My nation; / For instruction will go out from Me;/And I will set My judgment as a light for the peoples" (v. 4). God's judgment is a light. Thus, if we have His judgment, we have His light. Otherwise, we are in darkness.
In verse 5 Jehovah goes on to speak of His righteousness and salvation. "My righteousness is near; My salvation has gone forth;/My arms will judge the peoples;/The coastlands will wait for Me."
Salvation and righteousness always go together. This is clearly indicated in verse 6, where Jehovah says, "Lift up your eyes to the heavens,/And look upon the earth beneath; / For the heavens will vanish away like smoke,/And the earth will wear out like a garment,/And those who dwell there will die in like manner;/But My salvation will be forever,/And My righteousness will not be abolished."
In verses 7 and 8 Jehovah speaks a word to those who know righteousness, to a people in whose heart is His instruction. He says to them, "Do not fear the reproach of man;/Do not be terrified at their revilings./For the moth will eat them up like a garment,/And the worm will eat them like wool;/But My righteousness will be forever,/And My salvation from generation to generation."