Les Lamentations 5:20 Midrash : Eikhah Rabbah, Pesikta Rabbati, Midrash Tehillim & Yalkut Shimoni

“Why do You forget us forever, forsake us for so long?” (Lamentations 5:20).
“Why do You forget us forever?” Rabbi Yehoshua bar Avin said: Jeremiah employed four expressions: Spurning, rejection, forsaking, and forgetting. Spurning and rejection, as it is written: “Did You spurn Judah, did Your soul reject Zion?” (Jeremiah 14:19). And he was answered by Moses, as it is written: “I did not spurn them and I did not reject them” (Leviticus 26:44). Forsaking and forgetting, as it is written: “Why do You forget us forever, forsake us for so long?” And he was answered by Isaiah, as it is written: “These too may forget, but I will not forget you” (Isaiah 49:15).
Rabbi Yehoshua ben Levi said: Jeremiah employed four expressions: Spurning, anger, forsaking, and forgetting. Spurning, he answered himself, as it is written: “So said the Lord: If the heavens above can be measured and the foundations of the earth below probed, I too will spurn all the descendants of Israel because of everything that they did, the utterance of the Lord” (Jeremiah 31:37).²⁷Since the heavens and earth cannot be measured, Israel will not be spurned. Anger, he was answered by Isaiah, as it is stated: “For I will not contend forever and I will not be eternally angry” (Isaiah 57:16).

... Teach us oh, teacher: once the Ninth of Av has ended, is everything permitted? R’ Chiyah the Great taught like this: once the Ninth of Av has ended, one is permitted to do anything. Why? Because it is like the case of a person whose dead is laid out before him, who is forbidden to eat meat or drink wine. Once the dead is buried, the mourner is permitted to do so. So to on the Ninth of Av one is a mourner – once the day has ended one is permitted to do anything. Even though we are permitted, we must always have a sigh in our hearts until the Holy One returns to her. The Holy One said to them: by your lives! I burnt her, as it says “From above He has hurled fire into my bones…” (Lamentations 1:13) I will build her, as it says “Yet again will I rebuild you, then you shall be built, O virgin of Israel…” (Jeremiah 31:3) Zion said to Him: Behold, I have been sitting thus for many years! I have counted the days from old and I have not been redeemed, therefore I have despaired. She said that my master has abandoned me. And from where do we learn that Zion said this? From that which is written regarding it “And Zion said, ‘The Lord has forsaken me, and the Lord has forgotten me.’” (Isaiah 49:14) ... Another explanation. “And Zion said, ‘The Lord has forsaken me…” (Isaiah 49:14) What is written before this? “Sing, O heavens, and rejoice, O earth, and mountains burst out in song, for the Lord has consoled His people, and He shall have mercy on His poor.” (Isaiah 49:13) Once Zion saw that the prophet recalled His people and His poor, but did not mention Zion or Jerusalem she said ‘the Lord has forsaken me, and the Lord has forgotten me.’ Immediately the Holy One replied and said to her: just as it is impossible for a woman to forget her sucking child, so to I am not able to forget you, “Shall a woman forget her sucking child, from having mercy on the child of her womb?” (Isaiah 49:15) She said to Him: Master of the world! How is that possible? There is no end to the evils I have done! I caused Your Holy Temple to be destroyed and I killed the prophets. R’ Berachia the Kohen said in the name of Rebbe: the Holy One said to her, I will forget your evil but I will not forget your good. “…These too shall forget, but I will not forget you.” (ibid.) I have forgotten “"These are your gods, O Israel…” (Exodus32:4) but “I am the Lord, your God…” (Exodus 20:2) I will not forget.

"My soul has pined for Your salvation" (Psalms 119:81), as Jeremiah said, "Why do You forget us forever?" (Lamentations 5:20), "You have spurned us and rejected us," but "Restore us to Yourself" (Lamentations 5:21). Similarly, it is said, "The harvest has passed, the summer has ended, and we are not saved" (Jeremiah 8:20), and David said, "How long, O Lord? Will You forget me forever?" (Psalms 13:2) and "You, O Lord, have knowledge; remember me and take note of me; avenge me of my persecutors. Do not, because of Your patience, lead me to disillusionment. Take note that I suffer disgrace for Your sake" (Jeremiah 15:15). You are patient, but our spirit is weak, and the longer You wait, the more our souls are consumed. Therefore, it is said, "My soul has pined for Your salvation." "My eyes fail from searching Your word, saying, 'When will You comfort me?'" (Psalms 119:82). Why did my eyes fail? Concerning this, it is written, "For a set time, an appointed time; though it tarries, wait for it, for it will surely come, it will not delay" (Habakkuk 2:3). The appointed times have passed, yet You have not comforted me. Therefore, it is said, "When will You comfort me?" "For I am like smoke, long neglected" (Psalms 119:83). However, Daniel said, "Many shall purify themselves and be cleansed and refined; the wicked shall act wickedly and none of the wicked shall understand, but the wise shall understand" (Daniel 12:10). We have already been refined and cleansed; we have already endured all manner of affliction, as it is said, "For I am like smoke, long neglected." There is no greater refinement than death, as it is said, "How many are the days of Your servant?" (Psalms 119:84). Even though You brought Israel out of Egypt, we fear that they will be subjugated in the midst of the building. If it is Your will, do for us as it is said, "Make known among the nations in our sight" (Psalms 79:10). The Holy One, Blessed be He, said to them, "You ask Me to act, and I shall indeed act, as it is said, 'I will repay Babylon and all the inhabitants of Chaldea for all the evil they have done to Zion in your sight'" (Jeremiah 51:24). "The wicked have dug pits for me" (Psalms 119:85). Israel said to the Holy One, Blessed be He, "The wicked have not dug one pit for me, but many." It is written in the Torah, "You shall not slaughter it and its young both in one day" (Leviticus 22:28), and concerning me it is written, "Upon the iniquity of their fathers they will stumble" (Hosea 10:14). It is written in the Torah, "He shall pour out its blood" (Leviticus 17:13), and concerning me it is written, "I have been poured out like water" (Psalms 22:15).