"He His Messenger and His Message" by Ayatullah Baqir al-Sadr provides a comprehensive analysis of the life and teachings of the Prophet Muhammad (PBUH) and the fundamental principles of Islam. The book delves into the concept of prophethood, the divine message delivered by the Prophet, and its implications for humanity. Ayatullah al-Sadr emphasizes the importance of understanding the Prophet's mission in the context of monotheism and the moral framework established by Islam.