Albert Barnes Commentary Isaiah 28:5

"In that day will Jehovah of hosts become a crown of glory, and a diadem of beauty, unto the residue of his people;" — Isaiah 28:5 (ASV)

In that day - This verse begins a new subject and affirms that while the kingdom of Israel would be destroyed, the kingdom of Judah would be preserved and restored (Compare to Isaiah 7–9).

Be for a crown of glory - He will reign there as its king, and He will guard and defend the remnant of His people there. This reign of Yahweh will be to them better than palaces, towers, walls, and fruitful fields, and will be a more glorious ornament than the proud city of Samaria was to the kingdom of Israel.

And for a diadem of beauty - A beautiful garland. The phrase stands opposed to the wreath of flowers or the diadem which was represented in Isaiah 28:1 and Isaiah 28:3 as adorning the kingdom and capital of Israel. Yahweh and His government would be to them their chief glory and ornament.

To the residue of His people - To the kingdom of Judah, comprising the two tribes of Judah and Benjamin. This doubtless refers to the comparatively prosperous and happy times of the reign of Hezekiah.