Zophar repeats the same idea for emphasis. These are things that Job will do if he does what Zopahr spoke of in verses 13 and 14. (See: [[rc://en/ta/man/translate/figs-parallelism]] and [[rc://en/ta/man/translate/figs-hypo)
"Take your rest" here is an idiom for "rest." The phrase "in safety" can be expressed with the word "safely." Alternate translation: "will rest safely" (See: [[rc://en/ta/man/translate/figs-idiom]] and [[rc://en/ta/man/translate/figs-abstractnouns]])