שמואל ב ח:טו קבלה: זוהר

Another explanation is that "The king by justice establishes the land" refers to King David, as it is written, "And David reigned over all Yisrael; and David executed judgment and righteousness to all his people" (II Shmuel 8:15). He established the land, and by his merit, it stood, "but he who exacts gifts overthrows it" refers to Rechav'am.