en_tn/isa/50/11.md

all you who light fires ... flames that you have ignited

This continues the metaphor from the previous verse of people who walk in darkness. Here people who try to live according to their own wisdom instead of trusting in Yahweh are spoken of as if they lit their own fires and carried about torches in order to see in the dark. (See: rc://en/ta/man/jit/figs-metaphor)

You will lie down in a place of pain

Here to "lie down" refers to dying. Dying painfully is spoken of as if it were lying down in a place where they will experience pain. Alternate translation: "You will die with great suffering" (See: rc://en/ta/man/jit/figs-euphemism and rc://en/ta/man/jit/figs-metaphor)