English Standard Version
Isaiah 55:51 “Come, all you who are thirsty,
come to the waters;
and you without money,
come, buy, and eat!
Come, buy wine and milk
without money and without cost!
...
5 Behold, you shall call a nation that you do not know, and a nation that did not know you shall run to you, because of the LORD your God, and of the Holy One of Israel, for he has glorified you.
What does it mean to glorify here?
The operative word פָאַר (pa'ar) occurs in 14 places in the OT and is used in four distinct but closely related ways:
Thus, פָאַר (pa'ar), with the exception of Deut 24:20, always means to bring honour to something or someone by improving its standing or reputation. This is done either by adornment, boasting about oneself, or honoring others.
In the case of Isa 55:5 we have:
Note the comments of Matthew Poole:
For he hath glorified thee; because the God of Israel, who is the only true God, will highly honour thee, by his singular presence with thee, by his almighty power accompanying thy word, and making it wonderfully effectual for the conversion of an innumerable company, both of Jews and Gentiles, and by confirming thy word with illustrious signs and miracles, and particularly by thy resurrection and glorious ascension. These and other like considerations were the motives which convinced the Gentiles that Christ was the true Messiah, and the religion which he taught was the true religion.
This prophecy of Isaiah appears to anticipate the High Priestly prayer of Messiah Jesus in John 17:4, 5 when He asked:
I have glorified [= honored/exalted] You on earth by accomplishing the work You gave Me to do. And now, Father, glorify [= honor/exalt] Me in Your presence with the glory [= honor/repuation] I had with You before the world existed.
Glorification always means the same. Firstly it is always something’ that is visible, obvious, undeniable. Secondly, the aspect that we ‘see’ is something beyond of, well outside of the capability of whatever we ‘see’ the glory reflected in. Which is another aspect, Glory is reflected, that is, God reflected.
If Glory is seen in ‘man’, then something we see in that man is from outside of him. Be it ‘joy’, ‘a healing’, ‘provision’, and so on.
But, creation also reflects Gods Glory. Any ‘honest’ person looking at creation, or the universe instinctively ‘knows’ it didn’t ‘just happen’. So the Israelites could ‘see/sense/feel’ Gods Glory In ‘a cloud’ that supernaturally lead and protected them.
Now, Glory can also be reflected in a nation. Say one that provides a ‘solution’, or is supernaturally prosperous despite it’s physical environment. Or perhaps in the way it was ‘formed’ in just one day, overnight!
So in your verse, Isaiah is simply referencing the covenant God made with Abraham.
Genesis 12:2 I will build a great nation from you. I will bless you and make your name famous. People will use your name to bless other people.
Gods Glory will be seen through his nation. It will. Because this was promised.
