Jamieson, Fausset and Brown on Isaiah 45:9

9. Anticipating the objections which the Jews might raise as to why God permitted their captivity, and when He did restore them, why He did so by a foreign prince, Cyrus, not a Jew (Is 40:27, &c.), but mainly and ultimately, the objections about to be raised by the Jews against God's sovereign act in adopting the whole Gentile world as His spiritual Israel (Is 45:8, referring to this catholic diffusion of the Gospel), as if it were an infringement of their nation's privileges; so Paul expressly quotes it (Ro 9:4-8, 11-21).

Let ... strive--Not in the Hebrew; rather, in apposition with "him," "A potsherd among the potsherds of the earth!" A creature fragile and worthless as the fragment of an earthen vessel, among others equally so, and yet presuming to strive with his Maker! English Version implies, it is appropriate for man to strive with man, in opposition to 2Ti 2:24 [Gesenius].

thy ... He--shall thy work say of thee, He ... ?