Jeremiah predicts 4 times that in the day of the LORD God will judge Israel. He will "fight against them" and they shall "die of grievous deaths" AND "they shall not be gathered, nor be buried; they shall be for dung upon the face of the earth". They shall not be lamented:
[Jer 8:2 KJV] (2) And they shall spread them before the sun, and the moon, and all the host of heaven, whom they have loved, and whom they have served, and after whom they have walked, and whom they have sought, and whom they have worshipped: they shall not be gathered, nor be buried; they shall be for dung upon the face of the earth.
[Jer 16:4, 6 KJV] (4) They shall die of grievous deaths; they shall not be lamented; neither shall they be buried; but they shall be as dung upon the face of the earth: and they shall be consumed by the sword, and by famine; and their carcases shall be meat for the fowls of heaven, and for the beasts of the earth. ... (6) Both the great and the small shall die in this land: they shall not be buried, neither shall men lament for them, nor cut themselves, nor make themselves bald for them:
[Jer 25:33 KJV] (33) And the slain of the LORD shall be at that day from one end of the earth even unto the other end of the earth: they shall not be lamented, neither gathered, nor buried; they shall be dung upon the ground.
Because [the leadership of] apostate Israel had rejected and killed the Messiah, the Messiah would have no pity upon them. He would not mourn when the names of sinners are forever erased. God counts it a righteous thing:
[2Th 1:3-10 ESV] (3) We ought always to give thanks to God for you, brothers, as is right, because your faith is growing abundantly, and the love of every one of you for one another is increasing. (4) Therefore we ourselves boast about you in the churches of God for your steadfastness and faith in all your persecutions and in the afflictions that you are enduring. (5) This is evidence of the righteous judgment of God, that you may be considered worthy of the kingdom of God, for which you are also suffering-- (6) since indeed God considers it just to repay with affliction those who afflict you, (7) and to grant relief to you who are afflicted as well as to us, when the Lord Jesus is revealed from heaven with his mighty angels (8) in flaming fire, inflicting vengeance on those who do not know God and on those who do not obey the gospel of our Lord Jesus. (9) They will suffer the punishment of eternal destruction, away from the presence of the Lord and from the glory of his might, (10) when he comes on that day to be glorified in his saints, and to be marveled at among all who have believed, because our testimony to you was believed.
However, the doomed wicked mourn over the doomed wicked:
[Rev 18:9 KJV] (9) And the kings of the earth, who have committed fornication and lived deliciously with her, shall bewail her, and lament for her, when they shall see the smoke of her burning,
[Rev 18:20 ESV] (20) Rejoice over her, O heaven, and you saints and apostles and prophets, for God has given judgment for you against her!"
