en_tn_condensed/isa/45/21.md

General Information:

Yahweh continues speaking to the refugees. (See: Isaiah 45:20)

Let them conspire together

Here the word "them" refers to the refugees from among the nations who worship idols.

Who has shown this from long ago? Who announced it? Was it not I, Yahweh?

Yahweh uses questions to emphasize that he was the one who told them these things would happen. Alternate translation: "I will tell you who has shown this from long ago. I will tell you who announced it. It was I, Yahweh." (See: rc://en/ta/man/translate/figs-rquestion)