In The Problem of Dealing with the Prophet’s Sunnah (originally in Arabic), Al-'Alwani proposes a comprehensive and coherent concept of Prophet Muhammad’s Sunnah based on the linguistic, Qur'anic and Prophetic usages of the term Sunnah, and argues that a prophet’s saying, action or approval is authentic if evidently rooted in the Qur'an, not only narrated in a correct, honest and accurate way. Al-'Alwani stresses the Prophet’s humanness and contends that the Qur'an proves his fallibility in his ijtihad and corrects it if it was not in full conformity with the Qur'an. Hence, the Qur'an’s authority over the Sunnah. Al-'Alwani links the authentic legislative Sunnah to the Qur'an and denies that one source can abrogate the other because there can be no contradiction between them. He argues that the authentic legislative Sunnah constitutes no laws; rather, it only illustrates the Prophet’s interpretation and implementation of the laws already constituted in the Qur'an. Hence, Al-'Alwani’s argument that the Qur'an is the only constitutive source of Islamic law. He asserts that the Qur'an contains all laws explicitly or implicitly, and the Sunnah is its application. Al-'Alwani sends a clear message in this book, that is, the unity of Muslim Ummah can be reestablished only through the recognition of the Qur'an’s role in life, and the Prophet’s role in implementing it.