For I know their works and their thoughts: it shall come, that I will gather all nations and tongues; and they shall come, and see my glory.
For I (knew) - know is not in the Hebrew. Rather, understand the words by Aposiopesis: it is usual in threats to leave the persons threatened to supply the hiatus from their own fears, owing to conscious guilt: 'For I ... their works and thoughts'-namely, will punish (Maurer.)
It shall come that I will - the time is come that I will, etc.
Gather all nations - against Jerusalem where the ungodly Jews shall perish; and then the Lord at last shall Gather all nations - against Jerusalem, where the ungodly Jews shall perish; and then the Lord at last shall fight for Jerusalem against those nation; and the survivors (Isaiah 66:19) shall "see God's glory" (Zechariah 12:8-9; Zechariah 14:1-3; Zechariah 14:9).
And tongues - which have been many, owing to sin, being confounded at Babel, but which shall again be one in Christ (Daniel 7:14; Zephaniah 3:9; Revelation 7:9-10).