Midrasch zu Schir haSchirim 8:9

Resh Lakish was bathing himself in the Jordan, when Rabba b. b. Ghana came to him and shook hands with him. "God detests you Babylonians," said Resh Lakish to him, for it is written (Song. 8, 9) If she be a wall, we will build upon her a palace of silver; and if she be a door, we will enclose her with boards of cedar. This means: If you were all strong as a wall, and went with Ezra, you would have been like silver, which can never rot; but since you did not, you were like an Erez (a cedar) which is subject to decay. What kind of cedar is it over which decay has power? Ulla said: Sasmagur [a sawing worm to which a cedar is subject to decay]. And why do we liken the period of the second Temple into a Sasmagur? R. Abba said, this refers to a Bath Kol, as we are taught in the following Baraitha: With the death of the last prophets, Hagi, Zecharia and Malachi, the prophetic spirit was withdrawn from Israel, but they partook of [acted under] the holy inspiration (Bath Kol). (Is it possible that Resh Lakish spoke with Rabba b. b. Chana? If Resh Lakish would not speak with R. Elazar, who was the principal man in Palestine, because it was a rule that to whomsoever Resh Lakish spoke in the street, any business could be entrusted without witnesses, should Resh Lakish, then, have spoken with Rabba b. b. Chana [an inferior man]? R. Papa said: "Substitute another person. Either it was Resh Lakish and Ze'ri, or Rabba b. b. Ghana and R. Elazar.") When Resh Lakish came to R. Jochanan and related to him how he had explained the passage, R. Jochanan said to him: "This is not the reason [explanation]. If all had come with Ezra, even then the Shechina would not have abided in the second Temple, since it is written (Gen. 9, 27) May God enlarge the boundaries of Japheth, and may He dwell in the tents of Shem (Fol. 10); signifying, that although God enlarges the boundaries of Japheth, his Shechina can only dwell in the tents of Shem. And how is it known that the Persians are descendants of Japheth? Because it is written (Gen. 10, 2) The sons of Japheth: Gomer and Magog and Madai and Jaban and Tubal and Meshekh and Thirass; and R. Joseph has been taught that Thirass is Persia.

“If she is a wall, we will build upon her a silver turret; and if she is a door, we will affix upon her a cedar panel. I am a wall, and my breasts are like towers; then I was in his eyes as one who finds peace” (Song of Songs 8:9–10).
“If she is a wall, we will build upon her a silver turret”; “if she is a wall” – this is Abraham. The Holy One blessed be He said: If he stands firm in his convictions like a wall, “we will build upon her a silver turret” – we will rescue him and build him up in this world. “And if she is a door [delet], we will affix upon her a cedar panel” – if he is poor [dal] in mitzvot and sways to and fro in his actions like a door, “we will affix [natzur] upon her a cedar panel” – just as a drawing [tzura] exists only for a short while, so I will stand with him only for a short while.
“I am a wall” – Abraham said before the Holy One blessed be He: ‘I am a wall, and I will establish my good deeds like a wall.’ “And my breasts are like towers” – as I am destined to establish factions and groups of righteous men like me in the world.²³This is a reference to Abraham’s offspring. The term breasts is used to represent nourishing and raising the offspring. “Then I was in his eyes as one who finds peace” – the Holy One blessed be He said to him: ‘Just as you descended into the fiery furnace, so, I will extricate you intact.’ That is what is written: “I am the Lord who took you out of Ur²⁴Ur means fire in Aramaic. of the Chaldeans” (Genesis 15:7).

Rabbi Yoḥanan interpreted the verse regarding Sodom and Israel. “We have a [little] sister” (Song of Songs 8:8) – this is Sodom. That is what is written: “Your elder sister is Samaria […and your younger sister…is Sodom]” (Ezekiel 16:46). “And she has no breasts” (Song of Songs 8:8) – it did not suckle mitzvot and good deeds. “What shall we do for our sister on the day” (Song of Songs 8:8) that the supernal court decreed that it will burn in fire, as it is stated: “The Lord rained sulfur and fire on Sodom and on Gomorrah” (Genesis 19:24)?
“If she is a wall, we will build upon her” – this is Israel. The Holy One blessed be He said: If Israel stands firm in their deeds like a wall, we will build them up and rescue them. “And if she is a door” – if they sway in their words to and fro like a door, “we will affix [natzur] upon her a cedar panel.” Just as a drawing [tzura] exists only for a short while, so I will stand with him only for a short while.
“I am a wall” – Israel said before the Holy One blessed be He: ‘Master of the universe, we are a wall and we will stand firm like a wall in [performing] mitzvot and good deeds.’ “And my breasts are like towers” – as we are destined to establish factions and groups of righteous men like us in the world. “Then I was in his eyes as one who finds peace” – why? Because all the nations of the world were provoking Israel and saying to them: ‘If so, why did He exile you from His land, and why did He destroy His Temple?’ Israel would respond to them: ‘We are comparable to the daughter of a king who hurries to spend the festival in her father’s home. Ultimately, she returns to her home in peace.’²⁵Like a woman who left her husband’s home in order to visit her father’s home for a festival, Israel was sent into exile to the lands from which they had originally come. Eventually, they will return to their real home, the Land of Israel (Yefe Kol).
Another matter: “If she is a wall” – this is [a reference to] Ḥananya, Mishael, and Azarya. The Holy One blessed be He said: If Ḥananya, Mishael, and Azarya stand firm in their deeds, we will build the world upon them and rescue them. “And if [she is] a door” – if they sway in their deeds to and fro like a door, “we will affix [natzur] upon her a cedar panel.” Just as a drawing [tzura] exists only for a short while, so I will stand with them only for a short while.
“I am a wall” – they said before the Holy One blessed be He: ‘We will stand firm in mitzvot and good deeds like a wall.’ “And my breasts are like towers” – as we are destined to establish in Your world factions and groups of righteous men like us. “Then I was in his eyes as one who finds peace” – the Holy One blessed be He said to them: ‘Just as you descended into the fiery furnace intact, so I will extricate you intact.’ That is what is written: “Then Shadrakh, Meshakh, and Aved Nego emerged [from within the fire]” (Daniel 3:26).