What is the evidence for celebrating the death anniversaries of certain individuals in history (e.g. Abu Bakr, Umar, etc.)?
In the Name of Allah, the All-Beneficent, the All-Merciful.
May Allah bless Muhammad and his Family and damn their enemies.
Celebrating the death of hypocrites and oppressors is acceptable both logically as well as lawfully by Islam. It has been reported in more than one narration that the pure Infallibles (peace be upon them) celebrated the death of the tyrant Umar, son of al-Khattab (may the wrath of Allah be upon him). Also, Imam Zainul Abideen (peace be upon him) prostrated in thankfulness to Allah, the Most Exalted, when the news of the death of Abdullah, son of Ziyad, had reached him.
The Commander of the Believers (peace be upon him) used to say in one of his supplications:
O my Lord! He upon whom is thy blessings; our blessings are upon him and he upon whom is Your execration, then our execration is upon him. O, my Lord! He in whose death is joy [relief] for us and all Muslims, liberate us from him and give us in his place one who is better for us than him. This is so that we behold the manifestation of Your answer; the one we acknowledge in our faith and our lives – O most Merciful of the merciful.
Amali al-Mufid, pg. 166
Pay attention to what the Commander (peace be upon him) said in this holy supplication:
O my Lord in whose death is joy [relief] for us.
This proves that feeling joy for the death of tyrants is certainly legitimate and so is celebrating and showing the feelings of joy and happiness on such occasions.
The pure Imams (peace be upon them) used to praise Allah, the Most Exalted, celebrate and show feelings of joy when the chief of a certain deviant group dies during their time. You may refer back to the books of biographical evaluation such as Rijal al-Kashi.
Also, celebrating the death of tyrants and showing a feeling of happiness on such occasions is a manifesting of the doctrinal principle of Dissociation from the enemies of Allah. By doing so, one is adhering to the Prophet’s command, for he said regarding the people of innovation and suspicion:
If you find the people of innovation and suspicion after me, then demonstrate disassociation from them and address them with much words of condemnation.
al-Kafi, volume 02, page 375
The Office of Sheikh al-Habib