Charles Ellicott Commentary Zechariah 8:3

"Thus saith Jehovah: I am returned unto Zion, and will dwell in the midst of Jerusalem: and Jerusalem shall be called The city of truth; and the mountain of Jehovah of hosts, The holy mountain." — Zechariah 8:3 (ASV)

Compare to Zechariah 2:10-13.

Of truth — that is, where truth and fidelity towards God have their home , the faithful city. (For the other two titles, see Isaiah 2:2-3; Jeremiah 31:23.) Zion shall return to her former condition of faithfulness, and consequent favour with God. (Compare to Zechariah 8:8.)