Isaiah 49: 9-12
9 That thou mayest say to the prisoners, Go forth; to them that are in darkness, Shew yourselves. They shall feed in the ways, and their pastures shall be in all high places.
10 They shall not hunger nor thirst; neither shall the heat nor sun smite them: for He that hath mercy on them shall lead them, even by the springs of water shall He guide them.
11 And I will make all My mountains a way, and My highways shall be exalted.
12 Behold, these shall come from far: and, lo, these from the north and from the west; and these from the land of Sinim.
Verse 9 is the second time the loosing of prisoners is mentioned in Isaiah (42:7). It refers to the liberation of the righteous souls from sheol when Christ was resurrected and ascended to heaven. This seems confirmed by the fact that the reference to loosing prisoners is followed by statements referring to life after death, both here and where the passage is quoted ( v 9-10 with Rev. 7:15-17).
These prisoners are spoken of as having the Messiah as their Shepherd. He will:
Feed them in the ways-along the paths in which He leads them
Give them pastures in high places
Satisfy them so that they will never hunger or thirst
Protect them from the heat of the sun
Lead them all their days
Guide them to springs of living water
The hills and mountains of Arabian deserts, Horeb, Sinai, and some other places in Palestine are utterly destitute of vegetation; so if the Messiah will lead His people like a Shepherd to such places to feed in green pastures, it is proof that this refers to the Millennium when the desolate places will blossom like a rose (35:1-10).
Verse 10 is quoted in Rev. 7:16, proving a future fulfillment under the Messiah. The merciful Messiah will lead them to springs of living water (Rev. 7:15-17).
Verse 11 also refers to the Millennium when highways will be made from Egypt to Assyria through Palestine, and these countries will be blessed together (v. 11; 11:16; 19: 23-25).
Verse 12 pictures the regathering of Israel from all parts of the earth–from far, from north and west, and from Sinim. It is not clear where Sinim lies, but it seems to be contrasted with the west and may refer to the country of the extreme east, showing that the Jews will be gathered from all direction. Many think it refers to China. It is said that the Arabians and other Asiatics called China Sin or Tchin.