The cause of al-Hakam bin Amr's (may Allah be pleased with him) death was that he had supplicated against himself

It is narrated from Ahmad bin Sayyar that al-Hakam bin Amr, Rafi' bin Amr and Atiyyah bin Amr (may Allah be pleased with them) enjoyed the company of the Prophet (peace and blessings be upon him). Then Mu'awiyah (may Allah be pleased with him) appointed al-Hakam bin Amr governor of Khurasan. The cause of his death was that when he was in Marw, a letter from Ziyad and then (another) from Mu'awiyah (may Allah be pleased with him) reached him; after it was read, he supplicated (for death) upon himself, which was answered, and he died in Marw. Buraydah al-Aslami (may Allah be pleased with him) had died before him, so the two of them were buried in the Jassin cemetery in Marw, opposite the bathhouse of Abu Hamzah al-Sukkari. I have visited the graves of both of them.

It is narrated from al-Hasan al-Basri that Ziyad sent Sayyiduna al-Hakam bin Amr al-Ghifari (may Allah be pleased with him) as governor over Khurasan, and there the fighters obtained abundant spoils. So Ziyad wrote to him: "The Commander of the Believers (Mu'awiyah, may Allah be pleased with him) has written that the gold and silver be set aside specially for him and not be distributed among the Muslims." Al-Hakam (may Allah be pleased with him) wrote in reply: "You have mentioned the order of the Commander of the Believers, whereas I have found the Book of Allah (present) before the order of the Commander of the Believers. By Allah! If the heavens and the earth were closed up against a servant and he adopted piety (taqwa), Allah would make a way out for him." Then he had it announced: "Come to take your spoils," and he distributed them among the people. When Mu'awiyah (may Allah be pleased with him) received news of this, he sent a man who put him in shackles and imprisoned him. So he died in those very shackles and was buried in them. He had said (as a bequest): "I will present my case (on the Day of Resurrection)."

It is narrated from al-Hasan al-Basri that Ziyad sent Sayyiduna al-Hakam bin Amr al-Ghifari (may Allah be pleased with him) as the commander of an army. Sayyiduna Imran bin Husayn (may Allah be pleased with him) met him in the governor's house among the people and asked: "Do you know why I have come to you? Do you remember that when the Messenger of Allah (peace and blessings be upon him) was informed about the man whose commander had ordered him to jump into the fire, and the man stood up to jump, but the people held him back, the Messenger of Allah (peace and blessings be upon him) said: 'If he had jumped into it, both of them (the commander and the one commanded) would have entered the Fire; there is no obedience (to anyone) in disobedience to Allah'?" Al-Hakam (may Allah be pleased with him) said: "Yes (I remember)." Imran (may Allah be pleased with him) said: "I only intended to remind you of this hadith."
This hadith has a sahih (authentic) chain of narration, but the two Shaykhs did not record it.