For I will pour water - Floods, rivers, streams, and waters, are often used in the Scriptures, and especially in Isaiah, to denote plenteous divine blessings, particularly the abundant influences of the Holy Spirit (see the note at Isaiah 35:6-7). That it here refers to the Holy Spirit and his influences, is proved by the parallel expressions in the subsequent part of the verse.
Upon him that is thirsty - Or rather, ‘on the thirsty land.’ The word צמא tsâmē' refers here rather to land, and the figure is taken from a burning sandy desert, where waters would be made to burst out in copious streams (see Isaiah 35:6-7). The sense is, that God would bestow blessings upon them as signal and marvelous, as if floods of waters were made to descend on the dry, parched, and desolated earth.
And floods - The word נוזלים nôzelı̂ym, from נזל nâzal, “to flow,” to run as liquids, means properly flowings, and is used for streams and rivers Exodus 15:8; Psalms 78:16; Proverbs 5:15; Jeremiah 18 It means here that the spiritual influences which would descend on the afflicted, desolate, comfortless, and exiled people, would be like torrents of rain poured on the thirsty earth. This beautiful figure is common in the Scriptures:
He shall come down like rain upon the grass,
And as showers that water the earth.
My doctrine shall drop as the rain
My speech shall distil as the dew
As the small rain upon the tender herb,
And as the showers upon the grass.
I will pour my Spirit upon thy seed - (See Isaiah 59:21). This is in accordance with the promises everywhere made in he Bible to the people of God (see Genesis 12:7; Genesis 13:15; Genesis 15:18; Genesis 17:7-8; Exodus 20:6; Deuteronomy 7:9; Psalms 89:4; Isaiah 43:5). It may be regarded, first, as a promise of the richest blessings to them as parents - since there is to a parent’s heart no prospect so consoling as that which relates to his offspring; and, secondly, as an assurance of the perpetuity of their religion; of their return from captivity, and their restoration to their own land.