Solomon speaks to Yahweh as if he were speaking to someone else to show that he respects Yahweh. AT: "Yahweh, you have said that you" (See: [[rc://en/ta/man/translate/figs-123person]])
Here the word "thick" shows that the darkness is extreme. Yahweh spoke of not allowing sinful people to see him as if he were to live in darkness. AT: "in great darkness" (See: [[rc://en/ta/man/translate/figs-metaphor]])