For Zion's sake I will not (a) hold my peace, and for Jerusalem's sake I will not rest, until its righteousness shall go forth as (b) brightness, and its salvation as a lamp [that] burneth.
(a) The prophet says that he will never cease to declare to the people the good tidings of their deliverance.
(b) Till they have full deliverance: and this the prophet speaks to encourage all other ministers to the setting forth of God's mercies toward his Church.