Jamieson, Fausset and Brown on Isaiah 49:5

5. The reason why He was confident that His work would be accepted and rewarded, namely, because He is "glorious in the eyes of Jehovah," &c.

to bring Jacob again to him--(Mt 15:24; Ac 3:26).

Though Israel be not gathered--metaphor from a scattered flock which the shepherd gathers together again; or a hen and her chickens (Mt 23:37). Instead of the text "not," the Keri has the similar Hebrew word, "to Him," which the parallelism favors: "And that Israel may be gathered to Him."

yet--rather, parenthetically. "For I am glorious, &c., and My God is My strength." Then (Is 49:6) resuming the words from the beginning of Is 49:5, "He saith" (I repeat), &c. Horsley explains, "Notwithstanding the incredulity of the Jews, Messiah shall be glorified in the conversion of the Gentiles," reading as English Version: but if the Keri be read, "Israel shall at one time or other be gathered, notwithstanding their incredulity during Messiah's sojourn on earth."