Do not expect honesty and purity of intention from someone who has suffered from your malice; do not expect loyalty from one to whom you have been disloyal; do not expect goodwill from someone whom you regard with ill-will: his heart towards you is the same as your heart towards him.
Imam Naqi (A)
Excerpt from 'The Life of Imam 'Ali al-Hadi, Study and Analysis':
Imam al-Hadi (a.s.) became a heavy burden on al-Mu’tamid the Abbasid caliph after he saw people talk about the virtues, knowledge, asceticism, and piety of the Imam and prefer him to all other Muslim ulama’. He became angry, envious, and spiteful against the Imam His ill will led him to commit the worst crime in Islam.
He inserted fatal poison to the Imam, who, after having the poison, kept to bed. The poison reacted in all his body and he suffered intolerable pains. The Shi’a and the notables of the state visited him, and the all were covered with deep sorrow.
Imam al-Hadi (a.s.) appointed his son Abu Muhammad al-Hasan (al-Askari) as the Imam after him and set him as the general authority for the Shi’a after his death. He insinuated to his close companions about the Imamate of his son Abu Muhammad (a.s.) before. Imam al-Hadi (a.s.) entrusted his son Imam al-Hasan al-Askari (a.s.) with the procedures of funerals, prayer, and burial after his death, and recommended him of other recommendations concerning his affairs.
The poison reacted inside the body of Imam al-Hadi (a.s.). Violent pains attacked him and death approached him quickly. When he felt the inevitable death, he turned towards the qibla and began reciting some suras of the Qur'an. He breathed his last while the mention of Allah was still on his lips.
His great, pure soul ascended to its Creator surrounded by the angels. The earthly world turned dark while the Heavens shone bright to receive his coming. People lost much good by his death because it was the leader, guide, and defender of the rights of the weak and the oppressed that died.
Imam Abu Muhammad al-Hasan al-Askari (a.s.) washed the pure body of his father, enshrouded it, and offered the prayer of the dead on it while his heart was full of pain, sorrow, and regret.