Charles Ellicott Commentary Isaiah 41:27

"[I am the] first [that saith] unto Zion, Behold, behold them; and I will give to Jerusalem one that bringeth good tidings." — Isaiah 41:27 (ASV)

The first shall say to Zion.—The italics show the difficulty and abruptness of the original text. A preferable rendering is, (1) I was the first that said to Zion, etc. No oracle or soothsayer anticipated that message of deliverance (Ewald, Del.); or (2) a forerunner shall say ....

The words Behold them point to the returning exiles. The second clause fits in better with (2), and explains it. Jehovah sends a herald of good news (not Cyrus himself, but a messenger reporting his victories, or possibly Isaiah himself, as a more distant herald) to Jerusalem, to say that the exiles are returning.