(1) By the rivers of Babylon, There we sat down, yea, we wept, When we remembered Zion. (2) Upon the willows in the midst thereof We hanged up our harps. (3) For there they that led us captive asked of us words of song, And our tormentors asked of us mirth: ‘Sing us one of the songs of Zion.' (4) How shall we sing the LORD’S song In a foreign land? (5) If I forget thee, O Jerusalem, Let my right hand forget her cunning. (6) Let my tongue cleave to the roof of my mouth, If I remember thee not; If I set not Jerusalem Above my chiefest joy.
רב נחמן לר' יצחק מאי דכתיב (הושע יא, ט) בקרבך קדוש ולא אבוא בעיר משום דבקרבך קדוש לא אבוא בעיר א"ל הכי א"ר יוחנן אמר הקב"ה לא אבוא בירושלים של מעלה עד שאבוא לירושלים של מטה ומי איכא ירושלים למעלה אין דכתיב (תהלים קכב, ג) ירושלם הבנויה כעיר שחוברה לה יחדיו
Rav Nachman said to Rav Yitzhak: What does this mean: "There is something holy in your midst, and I [God] will not enter the city". (Hosea 11:9)
How could it be that "There is something holy in your midst, I will not enter the city?!"
Rav Yitzhak responded: Rabbi Yochanan taught the following explanation - God said: I will enter the [celestial] Jerusalem of Above until I come to the [earthly] Jerusalem below.
[Sage asks]: Is there a celestial Jerusalem?
Yes [reply of anonymous voice], as it is written in scripture: "The built up Jerusalem will be the city that is joined together with it". (Psalms 122:3)