John Trapp on Isaiah 32:15

Ver. 15. Ʋntill the Spirit be poured upon us from on high] Donec Dominus dignabitur ſuum favorem & gratiam denuo nobis impertiri, Till God ſhall pleaſe once more to impart unto us his grace and favour. So he ſets them no certain time of reſtauration: as deſirous thereby to ſtir them up to pray continually, and to bring forth fruits worthy amendment of life. This effuſion of the Spirit upon all fleſh, Joel 2.28. (that is, of the beſt thing upon the baſeſt) is a very great mercy.

And the wilderneſſe be a fruitful field] Heb. a Carmel: Such a change worketh the Spirit of grace; it maketh barren hearts fruitful, and manifeſteth hypocrites (whatever they ſeem) to be no better than wild trees that beare no good fruit.