- The personal rivalry  between the two brothers – one of whom, al-Ma’mun, was unquestionably superior in intelligence – only reflected a deeper opposition. That of the politico-religious tendencies that had begun to confront each other during the reign of Haroun and for which each of them had taken sides. Al-Amin relying on traditionalism and Arab culture, al Ma’mûn being in favor of innovative thought movements, marked by influences and foreign legacies that were particularly in favor of the populations of the eastern provinces.
The bishops, taking advantage of their new statutes, react to the king’s « laxity » towards the Jews and thus lay the foundations for an anti-Jewish policy that will remain in the Christian West for many centuries. Even until today.
- Without  even any artifice, the thing (the only choice left to the Jews must be conversion or exile) is confessed by Agobard, between 816 and 822-825, in his letter to Louis the Pious. He had undertaken missionary work with the Jews of Lyons, at the same time as with those of Chalon and Macon. The success was particularly strengthened by the fact that, « all Sabbaths, the word of God was preached in the synagogues by our brothers and priests ».
(extract of the psalm 88 associated to this generation, verses 1 to 6 )
- A song with musical accompaniment of the sons of Korah, for the conductor, about the sick and afflicted one, a maskil of Heman the Ezrahite.
- O Lord, the God of my salvation! I cried by day; at night I was opposite You.
- May my prayer come before You; extend Your ear to my supplication.
- For my soul is sated with troubles, and my life has reached the grave.
- I was counted with those who descend into the Pit; I was like a man without strength.
- I am considered among the dead who are free, as the slain who lie in the grave, whom You no longer remember and who were cut off by Your hand.
(extract of the psalm 88 associated to this generation, verses 7 and 8 )
- You have put me into the lowest pit, into dark places, into depths.
- Your wrath lies hard upon me, and [with] all Your waves You have afflicted [me] constantly.
(extract of the psalm 88 associated to this generation, verse 9 )
- You have estranged my friends from me; You have made me an abomination to them; [I am] imprisoned and cannot go out.
(extract of the psalm 88 associated to this generation, verses 10 to 16 )
- My eye has failed because of affliction; I have called You every day, I have spread out my palms to You.
- Will You perform a wonder for the dead? Will the shades rise and thank You forever?
- Will Your kindness be told in the grave, Your faith in destruction?
- Will Your wonder be known in the darkness, or Your righteousness in the land of oblivion?
- As for me, O Lord, I have cried out to You, and in the morning my prayer comes before You.
- Why, O Lord, do You abandon my soul, do You hide Your countenance from me?
- I am poor, and close to sudden death; I have borne Your fear, it is well-founded.
(extract of the psalm 88 associated to this generation, verses 17 to 19 )
- Your fires of wrath have passed over me; Your terrors have cut me off.
- They surround me like water all the day; they encompass me together.
- You have estranged from me lover and friend; my acquaintances are in a place of darkness.
 Janine Sourdel and Dominique Sourdel: « Historical Dictionary of Islam ». Heading al Ma’mûn (French: « Dictionnaire historique de l’Islam ». Rubrique al Ma’mûn (p. 529, 530) ).
 Conclusion by André Clot (« Muslim Spain », Chapter: « The Umayyad Emirs », page 66) following the preceding quotation. (French: « L’Espagne musulmane ». Chapitre : « Les émirs Omeyyades » p. 66) ).
 Bernhard Blumenkranz: « Jews and Christians in the western world 430-1096 ». Chapter III: « The Intellectual Encounter » (French: « Juifs et Chrétiens dans le monde occidental 430-1096 ». Chapitre III : « La rencontre intellectuelle » (p. 94) ).