It was narrated from Abū Tālib that he said to Abū ‘Abdillah (Ahmad bin Hanbal) that they passed in Tarsūs by the grave of a man, so the people of Tarsūs said:
“ ‘The Kāfir, may Allāh not forgive him’. So Abū ‘Abdillah said: “Yes, may Allāh not forgive him, he is the one who initiated / established this (the mihna, the Fithnah of Khalq Al-Quran) and came with it.”
[as-Sunnah no 1708 by al-Khallāl
The mentioned Kāfir is the ’Abbāsid caliph al-Ma’mūn and his grave is known till this day in Tarsūs. (Picture from Google)
Banū al-‘Abbās also had promoters of the creed of Ahl as-Sunnah, namely al-Mutawakkil ‘alā-llāh, who ended the Mihnā and let the narrations the Jahmiyyah rejected (like the narration of Mujāhid) be read by the scholars of the Ahl al-Hadīth to the people (mentioned by al-Khallal).
Source: Twitter @alshaybaani
Saheehus-Seerah 