Rashi on Isaiah
Until...be poured upon us (יֵעָרֶה) He shall pour upon us. Comp. (Gen. 24:2) “And she emptied (וַתְּעַר) her pitcher.” An expression of pouring applies to spirit. Comp. (Zech. 12:10) “And I will pour upon the house of David...a spirit of grace.” Comp. also (Joel 3:1) “I will pour My spirit upon all flesh.”
Ibn Ezra on Isaiah
יערה Be poured. Niphal. עד יערה עלינו רוח Until the decreed evil, the approach of the King of Assyria to the land of Judah, be poured upon us. רוח signifies here the divine decree.
Rashi on Isaiah
shall be regarded as a forest (Jonathan renders:) Great cities, like this forest, which is full of trees.