C. F. Keil and Franz Delitzsch on Isaiah 52:8

Isa 52:8

How will the prophets rejoice, when they see bodily before them what they have already seen from afar! “Hark, thy watchers! They lift up the voice together; they rejoice: for they see eye to eye, how Jehovah bringeth Zion home.” קול followed by a genitive formed an interjectional clause, and had almost become an interjection itself (see Gen 4:10). The prophets are here called tsōphı̄m, spies, as persons who looked into the distance as if from a watch-tower (specula, Isa 21:6; Hab 2:1) just as in Isa 56:10. It is assumed that the people of the captivity would still have prophets among them: in fact, the very first word in these prophecies (Isa 40:1) is addressed to them. They who saw the redemption from afar, and comforted the church therewith (different from mebhassēr, the evangelist of the fulfilment), lift up their voice together with rejoicing; for they see Jehovah bringing back Zion, as closely as one man is to another when he looks directly into his eyes (Num 14:14). בּ is the same as in the construction בּ ראה; and שׁוּב has the transitive meaning reducere, restituere (as in Psa 14:7; Psa 126:1, etc.), which is placed beyond all doubt by שׁוּבנוּ in Psa 85:5.