Charles Ellicott Commentary Isaiah 9:7

"Of the increase of his government and of peace there shall be no end, upon the throne of David, and upon his kingdom, to establish it, and to uphold it with justice and with righteousness from henceforth even for ever. The zeal of Jehovah of hosts will perform this." — Isaiah 9:7 (ASV)

Of the increase ... —Better, “For the increase of the government, and for peace with no end ... The “throne of David,” though in harmony with the whole body of prophetic tradition regarding the Messiah, may be noted as the first appearance of that tradition in Isaiah.

Henceforth even for ever. —The words can be interpreted, as in the parallels of Psalm 21:4; Psalms 61:6–7; 2 Samuel 7:12–16, as referring to the perpetuity of the dynasty that the anointed king is to found; but the “Everlasting Father” of the context, and the parallels of Psalm 45:6; Psalms 110:4, favor its reference to a personal immortality of sovereignty.

The zeal of the Lord of hosts will perform ... —As in Greek so in Hebrew, we have the same root-word and root-idea for “zeal” and “jealousy,” and here, perhaps, the latter thought is dominant. It is because Jehovah loves the daughter of Zion with an absorbing love that He purposes such great things for her future, and that what He purposes will be assuredly performed. (Compare Ezekiel 5:13.)