Isaiah 26:20

Before the restoration of Israel, however, God’s people would experience hard times (in the Tribulation, cf. Revelation 12). Before God opened the gates of the new city to the redeemed (Isaiah 26:2), they would need to shut their doors against their foes (cf. Genesis 7:1; Genesis 7:16; Exodus 12:22-23). Shutting the doors suggests both safety from danger and separation from others, in this case, pagans.