Muawiyah wished to pass the caliphate to his own son Yazid ibn Muawiyah, and saw Hasan ibn Ali as an obstacle to his plans. And thus Muawiyah plotted to kill Hasan ibn Ali. He secretly contacted Hasan ibn Ali's wife Ja'da bint al-Ash'ath ibn Qays, and instigated her to poison her husband. Ja'da did as Muawiyah suggested, giving her husband poison mixed with honey. Madelung (pp. 331–333) notes other traditions suggesting that Hasan ibn Ali had ...