This message is in the form of a parable. The worthless thistle represents Amaziah, and the cedar represents Jehoash. The trampling of the thistle by the beast expresses that something bad will happen to the thistle, and it will be powerless to stop it. The point of the parable is that Amaziah was foolish to challenge Jehoash. (See: [[rc://en/ta/man/translate/figs-parables]])
This is an idiom that means he had become proud. AT: "you have become proud" (See: [[rc://en/ta/man/translate/figs-idiom]])
# why should you cause yourself trouble and fall, both you and Judah with you?
Jehoash used this rhetorical question to warn Amaziah not to fight with him. It can be translated as a statement. AT: "you should not cause yourself trouble and fall, both you and Judah with you." (See: [[rc://en/ta/man/translate/figs-rquestion]])
# fall
Here "fall" is a euphemism for "die." (See: [[rc://en/ta/man/translate/figs-euphemism]])