Albert Barnes Commentary Isaiah 17:3

"And the fortress shall cease from Ephraim, and the kingdom from Damascus, and the remnant of Syria; they shall be as the glory of the children of Israel, saith Jehovah of hosts." — Isaiah 17:3 (ASV)

The fortress – The strong place of defense; the fortified place.

Shall cease – Shall come to an end; shall cease to be, for so the word שׁבת (shâbath) is often used (Genesis 8:22; Isaiah 24:8; Lamentations 5:15).

From Ephraim – The name given to the kingdom of Israel, or the ten tribes, because Ephraim was the largest of the ten, and was a leading tribe in their councils (see the note at Isaiah 7:2). Ephraim, or the kingdom of Samaria, is mentioned here in connection with Damascus or Syria, because they were confederated together and would be involved in the same overthrow.

And the remnant of Syria – That which is left of the kingdom of Syria after the capital, Damascus, shall be destroyed.

They shall be as the glory of the children of Israel – That is, as the defenses, or the strongly fortified towns and strongholds of the kingdom of Israel shall pass away or be destroyed, so shall it be with the kingdom of Damascus. As they are allied with each other, they shall fare alike. The Chaldee reads this: ‘And the dominion shall cease from Ephraim, and the kingdom from Damascus.’