His power, presence and protection
Isa 4:4 When the Lord shall have washed away the filth of the daughters of Zion, and shall have purged the blood of Jerusalem from the midst thereof by the spirit of judgment, and by the spirit of burning.
The filth of the daughters of Jerusalem will be cleansed of their sins by the blood of Jesus and the Baptism of His Spirit.
Mat 3:11 I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and with fire:
Mat 3:12 Whose fan is in his hand, and he will thoroughly purge his floor, and gather his wheat into the garner; but he will burn up the chaff with unquenchable fire.
Isa 4:5 And the LORD will create upon every dwelling place of mount Zion, and upon her assemblies, a cloud and smoke by day, and the shining of a flaming fire by night: for upon all the glory shall be a defence.
The presence of the Lord will be with his people as in the time of Moses, only it will stay with them. The indwelling of the Holy Spirit.
Exo 13:21 And the LORD went before them by day in a pillar of a cloud, to lead them the way; and by night in a pillar of fire, to give them light; to go by day and night:
Exo 13:22 He took not away the pillar of the cloud by day, nor the pillar of fire by night, from before the people.
Isa 4:6 And there shall be a tabernacle for a shadow in the daytime from the heat, and for a place of refuge, and for a covert from storm and from rain.
Jesus our refuge and our protection.
Psa 61:2 From the end of the earth will I cry unto thee, when my heart is overwhelmed: lead me to the rock that is higher than I.
Psa 61:3 For thou hast been a shelter for me, and a strong tower from the enemy.
Psa 61:4 I will abide in thy tabernacle for ever: I will trust in the covert of thy wings. Selah.