O Lord, thou art my God - The prophet speaks, not in his own name, but in the name of the people that 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, they now had demonstration that he was their God.
I will exalt thee - A form of expression often used to denote praise Psalms 118:28; Psalms 145:1, meaning that the worshipper would exalt God in the view of 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 - Which were formed and revealed long since. The counsels referred to are those respecting the delivery of his people from bondage, which had been expressed even long before their captivity commenced, and which would be now completely and triumphantly fulfilled.
Are faithfulness - Have been brought to pass; do not fail.
And truth - Hebrew, אמן 'omen - whence our word Amen. Septuagint, Γένοιτο Genoito - ‘Let it be.’ The word denotes that the purposes of God were firm, and would certainly be fulfilled.