en_tn/2sa/18/13.md

a falsehood

The word "falsehood" can be expressed with a verb phrase. Also, this refers to disobeying the king's command. This can be stated clearly. Alternate translation: "doing something that is wrong" or "by disobeying the king" (See: rc://en/ta/man/translate/figs-abstractnouns and rc://en/ta/man/translate/figs-explicit)

there is nothing hidden from the king

Here the man speaks about how the king knows about almost everything that happens as if everything were a physical object he knew the location of. Alternate translation: "there is nothing that the king does not know" or "the king hears about everything that happens" (See: rc://en/ta/man/translate/figs-metaphor)