Possible meanings are 1) Moses is calling on all those who live in heaven and earth to be witnesses to what he says or 2) Moses is speaking to heaven and earth as if they are people, and he is calling them to be witnesses to what he says. (See: [[rc://en/ta/man/jit/figs-metonymy]] and [[rc://en/ta/man/jit/figs-personification]])
Long days are a metaphor for a long life. Alternate translation: "you will not be able to live a long time" (See: [[rc://en/ta/man/jit/figs-metaphor]])
As indicated in 4:27, not every Israelite will be killed. Here "completely destroy" is a generalization and emphasizes that many of the Israelites will die. This can be stated in active form. Alternate translation: "but Yahweh will destroy many of you" (See: [[rc://en/ta/man/jit/figs-hyperbole]] and [[rc://en/ta/man/jit/figs-activepassive]])