Isaiah 43: 8-9. “Bring forth the blind people that have eyes, and the deaf that have ears. Let all the nations be gathered together, and let the people be assembled: who among them can declare this, and shew us former things? let them bring forth their witnesses, that they may be justified: or let them hear, and say, it is truth.”
Blind people that have eyes and deaf people with ears refer to Israel (v. 8 with 42:18-22). All nations refers to the Gentiles. The purpose here was to assemble all people to hear the challenge of God , to witness His choice of making Israel His special people to fulfill His will in propagating the truth among all nations, and to demonstrate their power or lack of it to prophesy so they might acknowledge that what God had predicted was the truth.
Who among the whole multitude of both Jews and Gentiles can declare and show things that are to happen? Let them demonstrate their prophetic powers so they can be justified in their claims that Jehovah is not the only one who has this power.