Matthew Poole and continuators on Isaiah 48:18

18. O that thou hadst hearkened to my Commandements , then had thy peace been as a river , and thy righteousness as the waves of the sea .

The failure hath not been on my part, but on thine: I gave thee my Counsels and Commands, but thou hast neglected and disobeyed them, and that to thy own great disadvantage. Such wishes as these are not to be taken properly, as if God longed for something, which he gladly would but could not effect; or as if he wished that to be undone, which was irrecoverably past and done; which is a vain and foolish wish even in a Man; and much more are such wishes inconsistent with the infinite perfection and happiness of the divine Nature: but they are onely significations of God's good and holy Will, whereby he requires and loves Obedience, and condemns and hates Disobedience.

Which runs Sweetly, Strongly, Plentifully, and Constantly; and such had been thy Prosperity. Then thou hadst never gone into this Babylonish Captivity, nor needed such prodigies of my power and goodness to Deliver thee out of it.

Not properly so called (for he is not now speaking of their Vertues, but of their Priviledges) but thy Peace and Prosperity, as appears by the foregoing Clause, to which this manifestly answers; which is called Righteousness here, as it is also, 1 Sam. 12. 7. and Hos. 10. 12. and elsewhere, by a Metonymy, because it is the fruit of Righteousness both of God's Righteousness, and of Man's Righteousness; as by the very same figure, iniquity is very frequently put for the fruit and punishment of iniquity.

Infinite and continual.