כִּלָּ֤ה יְהוָה֙ אֶת־חֲמָת֔וֹ שָׁפַ֖ךְ חֲר֣וֹן אַפּ֑וֹ וַיַּצֶּת־אֵ֣שׁ בְּצִיּ֔וֹן וַתֹּ֖אכַל יְסוֹדֹתֶֽיהָ׃ (ס)
גאָט האָט אױסגעלאָזט זײַן כּעס, אױסגעגאָסן זײַן גרימצאָרן; און ער האָט אָנגעצונדן אַ פֿײַער אין צִיוֹן, און עס האָט פֿאַרצערט אירע גרונטפֿעסטן.
Rashi
into heaps Now what is this song? Is it not a lamentation? But because it says (Lam. 4:11): “The Lord has spent His fury.” With what has He spent it? “He has kindled a fire in Zion.” This is a song and an occasion for singing, for He poured out His fury on the wood and stones and did not utterly destroy His children.
Malbim
In this way he also justifies his reproof of Job at the beginning of his first speech, when he had said: 'Was not your own security the reason for your piety?' (Job 4:6). For the essence of correct worship is that it should be performed without any expectation of repayment or fear of retribution, and in this Job had sinned, Therefore his steps faltered (Psalms 37:31), and God poured His wrath upon him (Lamentations 4:11).
Da'at Zekenim
שלם ישלם שנים, “must pay twice the value of what he had destroyed” The Talmud tractate Baba Kamma, folio 60, quotes G–d as having said: “I have lit a destructive fire in Zion,” (Lamentations 4,11) it therefore behooves Me when (the time comes) to pay for the destruction I have caused.” This is the deeper meaning of what the prophet Zecharyah has said in Zecharyah 2,9, “I will be for Zion a (protective) wall of fire all around it.”
Rashi
It aided him: While he was still bent before him; such that he understood one of the psalms in the book of Psalms that he had not understood [how] to expound beforehand. And some explain that he only expounded this one verse (Psalm 79:1): "A Song of Asaph, God, the nations invaded your inheritance" - It should have stated, "A Lament of Asaph." And he expounded thus - that Asaph said a song that the Holy One, blessed be He, consumed His anger on wood and stone that was in His house; and because of this, exonerated the survivors in Israel. For were it not for this, Israel (lit. the enemies of Israel) would not have left any survivors. And this is what it says, (Lamentations 4:11) "The Lord has spent His fury, He has poured out His fierce anger, and He has kindled a fire in Zion."
Rashi
משכנתיך How goodly are they even when they are in ruins, because then they are a pledge (משכון) for you, and the fact that they are in ruins is an atonement for your souls, as it is said. (Lamentations 4:11) “The Lord hath brought His fury to an end”. And by what means hath He brought it to an end? “He hath kindled a fire in Zion! (i.e. hath destroyed the Temple) (cf. Midrash Tanchuma, Mishpatim 11).