Possible meanings are 1) God is calling on all who live in heaven and on earth to be witnesses as he judges his people or 2) God is speaking to heaven and earth as if they are people, and he is calling them to be witnesses as he judges his people. (See: [[rc://en/ta/man/jit/figs-metonymy]] and [[rc://en/ta/man/jit/figs-personification]])