Here "hold fast" is a metaphor that represents being determined to continue to say something. The abstract noun "righteousness" can be expressed with "righteous." Alternate translation: "I am determined to continue saying that I am righteous" (See: [[rc://en/ta/man/jit/figs-metaphor]] and [[rc://en/ta/man/jit/figs-abstractnouns]])
Here "will not let it go" is a metaphor that represents not stopping saying something. Alternate translation: "will not stop saying that I am righteous" or "will not stop saying so" (See: [[rc://en/ta/man/jit/figs-metaphor]])
Here the phrase "my conscience" represents Job. Alternate translation: "even in my thoughts, I will not accuse myself" (See: [[rc://en/ta/man/jit/figs-metonymy]])