Thus saith the LORD; I have returned to Zion, and will dwell in the midst of Jerusalem: and Jerusalem shall be called a {b} city of truth; and the mountain of the LORD of hosts the holy mountain.

(b) Because she will be faithful and loyal toward me her husband.

Wesley's Notes

8:3 Shall be called a city of truth - Her citizens shall love the truth and speak it, shall worship me in truth of heart, as well as in the true manner prescribed to them.

Scofield Reference Notes

[1] holy mountain

Holiness, Sanctification, Summary: In the O.T. the words consecration, dedication, sanctification, and holiness are various renderings of one Hebrew word, are used of persons and of things, and have an identical meaning, i.e. set apart for God. Only when used of God himself (e.g. Lev 11:45), or of the holy angels (e.g. Dan 4:13) is any inward Lev 11:45 Dan 4:13 moral quality necessarily implied. Doubtless a priest or other person set apart to the service of God, whose whole will and desire went with his setting apart, experienced progressively an inner detachment from evil; but that aspect is distinctively of the N.T., not of the O.T. Mt 4:5.

Jamieson-Fausset-Brown Bible Commentary

3. I am returned-that is, I am determined to return. My decree to that effect is gone forth.

Jerusalem . city of truth-that is, faithful to her God, who is the God of truth (Isa 1:21, 26; Joh 17:17). Never yet fully fulfilled, therefore still to be so.

the mountain of the Lord-(Isa 2:2, 3).

holy mountain-(Jer 31:23).

Matthew Henry's Concise Commentary

8:1-8 The sins of Zion were her worst enemies. God will take away her sins, and then no other enemies shall hurt her. Those who profess religion must adorn their profession by godliness and honesty. When become a city of truth and a mountain of holiness, Jerusalem is peaceable and prosperous. Verses 4,5, beautifully describe a state of great outward peace, attended with plenty, temperance, and contentment. The scattered Israelites shall be brought together from all parts. God will never leave nor forsake them in a way of mercy, for this he has promised them; and they shall never leave nor forsake him in a way of duty, as they have promised him. These promises were partly fulfilled in the Jewish church, betwixt the captivity and the time of Christ's coming; and they had fuller accomplishment in the gospel church; but the full import must be as to the future times of the Christian church, or the future restoration of the Jews. With men this is impossible, but with God all things are possible; so far are God's thoughts and ways above ours. In the present low state of vital godliness, we can hardly conceive that so complete a change can be made; but a change thus extensive and glorious, can be brought to pass by the almighty power of the new-creating Spirit, in less time than he was pleased to employ in creating the world. Let the hands of all who labour in the cause of the gospel be strong, serving the Lord in true holiness, assured that their labour shall not be in vain.