The Islamic world received the government of al-Mehdi with more joys and delights. That is because of what it had met during the time of al-Mansur such as severity, strictness, and tyranny in the governing they ended with his death. For al-Mehdi was more tractable than his father and was famous for generosity, open-handedness, refraining from severity and rudeness.
When al-Mehdi ascended the throne, he issued a royal decree to release all the political detainees and prisoners except those killers and mischief-makers. He also returned the movable and the immovable properties his father unjustly and aggressively confiscated to their owners. He returned to Imam Musa what his father had taken from Imam al-Sadiq, peace be on him. The reason for that is that he undertook the kingdom that led a life of stability and tranquility. Besides he received the great wealth his father had collected while he was stingy toward himself and the community; so neither he nor it enjoyed the blessings of that great wealth. Unfortunately, al-Mehdi spent that great wealth on amusement, dissoluteness, gifts to the hirelings and the dissolute. The weak class did not make use of it, for he did not give anything of it, and for he had no concern except satisfying his pleasures and going too far in lavish expenditure, luxury, and dissoluteness.
Any way al-Mehdi cannot be compared to his father, for he was contrary to him in most his qualities and deeds, but he inherited from his father an intense enmity toward the 'Alawids and their followers, for he detested them very much. He inherited that from his father al-Mansur, thought that he would not last in undertaking the government and authority except through destroying the 'Alawids and their followers. In the following we will deal with some of his qualities and his deeds and what Imam Musa, peace be on him, met during his time.
The Islamic Caliphate is the shadow of Allah on earth; therefore, it was necessary for it to represent the objectives, reality, and guidance of Islam; and it was necessary for it to be kept from futility and temptations, and to be far above amusement and dissoluteness. Any way it has not reported that many of the Umayyad and the 'Abbasid rulers were far away from the abominable things and amusement were forbidden by Allah. For they turned the Islamic caliphate into theaters for dance, pleasure, and corruption. If they had taken off the garment of the caliphate, they would have preserve Islam and kept its ideals.
Amusement, dissoluteness, liquidity, and corruption spread among the people during the time of al-Mehdi. Bashshar's poems circulated; the people memorized