12. he will be a wild man--literally, "a wild ass man," expressing how the wildness of Ishmael and his descendants resembles that of the wild ass.
      his hand will be against every man--descriptive of the rude, turbulent, and plundering character of the Arabs.
      dwell in the presence of all his brethren--dwell, that is, pitch tents; and the meaning is that they maintain their independence in spite of all attempts to extirpate or subdue them.

JFB.