Al-Hasan al-Basri narrates: Ziyad used to hunt down the partisans of Ali and kill them. When this reached Sayyiduna Imam Hasan bin Ali (may Allah be pleased with them both), he said: "O Allah, grant him a natural death, for being killed is an expiation."
Al-Tabarani recorded it, and its narrators are the narrators of the Sahih.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الحدود والديات / 10604