Hasan withdrew to Medina and lived there for about a decade without political activity. He is reported to have died of poison, and a large part of the tradition names one of his wives as the agent and Muawiya as the instigator, with an offer of marriage to Yazid as the inducement. Sunni and Shia sources weigh the reports differently; the poisoning is close to universal in Shia accounts and is present but contested in Sunni ones, and no version rests on evidence that would settle it.
He had asked to be buried beside his grandfather in the Prophet's chamber. The request was refused, by accounts naming the governor Marwan and Aisha's objection, and the family was met by armed opposition when it approached; the brother, Husayn, was persuaded not to force it. He was buried instead in the Baqi cemetery on the edge of Medina, alongside other members of the household.
Domed structures were built over those graves and stood for centuries as a pilgrimage site. They were demolished in 1925 and 1926, after the Saudi conquest of the Hijaz, in accordance with a reading of Islamic law that treats built tombs as an occasion of associating partners with God. The site is now open ground with the graves unmarked.
The demolition is commemorated annually as Yawm al-Hadm, the day of the destruction, by Shia communities, and remains a live grievance in relations between them and the Saudi state. A man remembered chiefly for standing down from a conflict thus sits at the centre of a dispute that has not stood down at all.