Yea, do good, or do evil. Here the proof required of the idol-gods is changed. If they cannot prophesy, can they effect anything? Can they do either good or harm? Let them show this. It is a plain "abatement" from the first demand, and therefore properly introduced by "yea" (aph); comp.
1 Kings 8:27. That we may be dismayed; i.e. rather, perhaps, that we may look to it, or examine it; i.e. see if yon have really shown a power of doing anything.