In the above verse, the Prophet Yeshayahu (Isaiah) describes the day when Yerushalayim (Jerusalem) will be redeemed. Sitting on the ground, in the dust, is an expression of mourning. In this prophecy, Yeshayahu foretells the People of Israel and the city of Yerushalayim arising and shaking off the dust that has settled on them. This action would indicate that the period of grief and mourning is over and that the Holy City is being restored to her former beauty and splendor. Yerushalayim will then cast off the chains from her neck and once again be free. The Children of Israel who had likewise been held captive for so long, will be released and returned to their ancient homeland.
Source: Israel in the News