Concerning this; concerning this counsel or practice. Or, to her; to Jerusalem or Judah. Their strength is to sit still; it is safer and better for them to sit quietly at home, seeking to me for help. He seems industriously to use an ambiguous word, Rahab, which signifies both strength, as Job 9:13 Psalms 90:10, and Egypt, as Psalms 87:4 Isaiah 51:9, so called from its singular strength; to intimate that if they did not go to Rahab, Rahab, or what they expected from Rahab or Egypt, which was powerful succour, should come to them.
Related Commentaries of Isaiah 30:7
Isaiah 30:7
7 For the Egyptians shall help in vain, and to no purpose: therefore have I cried concerning this, Their strength is to sit still.