Is it permissible to say "God Almighty has spoken the truth" after finishing a recitation of the Qur'an, given that some consider it an innovation and cite His saying, "Say, 'God has spoken the truth. So follow the religion of Abraham, inclining toward truth'" (Al 'Imran/95), and that the Prophet, may God's prayers and peace be upon him, used to say "Enough for you" to stop the reciter?

People's habit of saying "صدق الله العظيم" (Allah, the Most Great, has spoken the truth) upon finishing the recitation of the Qur’an has no basis in Islamic law. Rather, it is an innovation (bid'ah) if one believes it to be a Sunnah. The verse "Say, 'Allah has spoken the truth'" (Al-Imran/95) does not indicate this, but rather it is a command to declare Allah's truthfulness in what He has revealed from the Books. It was not known for the Prophet, peace and blessings be upon him, nor for his companions, to say that after recitation. The Prophet, peace and blessings be upon him, said to Ibn Mas'ud, "Enough for you," when he recited the beginning of Surat An-Nisa' to him, and he did not ask him to say that. Therefore, it is legislated to abandon this addition, in emulation of the Prophet, peace and blessings be upon him, and his companions. However, doing it occasionally, unintentionally, does no harm, for Allah is truthful in all things.