Using force to cause them not to be proud is spoken of as if he were to break their pride. AT: "I will punish you and so end the pride that you feel about your power" or "I will punish you so that you will no longer be proud of your power" (See: [[rc://en/ta/man/translate/figs-metaphor]])
This means God will stop the rain from falling from the sky. This will make the ground hard so that people cannot plant seed or grow crops. (See: [[rc://en/ta/man/translate/figs-simile]])
Working very hard is spoken of as if they were to use all their strength until they had no more strength. The phrase "for nothing" means that they would get nothing from working so hard. AT: "You will work very hard in vain" or "You will work very hard, but you will not receive anything good from working so hard" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-idiom]])