The writer speaks about his enemies as if they were lions and wild oxen to emphasize how dangerous his enemies are. Also, the mouth and horns stand for the animals as a whole in a synecdoche. The writer emphasizes these parts of the animals because they are what the animals would use to kill someone. (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-synecdoche]])