Albert Barnes Commentary Isaiah 25:1

"O Jehovah, thou art my God; I will exalt thee, I will praise thy name; for thou hast done wonderful things, [even] counsels of old, in faithfulness [and] truth." — Isaiah 25:1 (ASV)

O Lord, thou art my God - The prophet speaks, not in his own name, but in the name of the people who would be delivered from bondage. The sense is that Yahweh had manifested himself as their covenant-keeping God; and that in view of his faithfulness in keeping his promises, it was now demonstrated to them that he was their God.

I will exalt thee - This is a form of expression often used to denote praise (Psalms 118:28; Psalms 145:1), meaning that the worshipper would exalt God in his own mind, or would regard him as above all other beings and objects.

For thou hast done wonderful things - On the meaning of the Hebrew, פלא pel' - ‘wonderful,’ see the note at Isaiah 9:6.

Thy counsels of old - These are counsels which were formed and revealed long ago. The counsels referred to are those concerning the delivery of his people from bondage, which had been expressed even long before their captivity commenced, and which would now be completely and triumphantly fulfilled.

Are faithfulness - They have been brought to pass; they do not fail.

And truth - Hebrew, אמן 'omen - from which our word Amen comes. Septuagint, Γένοιτο Genoito - ‘Let it be.’ The word denotes that the purposes of God were firm and would certainly be fulfilled.