Isaiah 4:3

Those who are left in Zion, who remain in Jerusalem, will be called holy, all who are recorded among the living in Jerusalem.

In the previous chapter we hear a scathing doom and gloom prophecy against Judah and Jerusalem.  In Israel, however, there is a remnant, survivors, those whom God will call holy.  Because of them, He will provide protection and a shelter.  We want to be part of the remnant, those who love God and honor Him in a society that seems to be going the other direction

Isaiah 3:10

Tell the righteous it will be well with them, for they will enjoy the fruit of their deeds.

In the midst of this scathing judgment on Israel comes verse 10.  God is faithful to reassure the righteous remnant not only that they will be cared for by Him, but also,  that they will enjoy the fruit of their deeds while the wicked will, instead, come to disaster.  Our righteousness is in Christ Jesus, the Saviour.  He is our Ark of Safety.