Ibn Ezra on Isaiah
סס The worm. It is hap. leg. But my righteousness shall be for ever. Comp. And His righteousness endureth for ever (Ps. 112:8).8I. E. comparing this phrase with a similar one (Ps. 112:3) explains the verb היה by the verb עמד, which more exclusively expresses duration, while היה has also the meaning to become, signifying a single act.