The Fortification of Faith by Shah Ismail Shaheed is a foundational Islamic text focused on the purification and strengthening of one's faith (Iman). Written in the 19th century, this book aims to eliminate misconceptions and practices of shirk (associating partners with Allah) that had infiltrated the beliefs and actions of Muslims. Shah Ismail Shaheed emphasizes the importance of pure monotheism (Tawhid) and adherence to the Quran and Sunnah, while strongly discouraging innovations (Bid'ah) and superstitious rituals.

The book serves as a guide for Muslims to fortify their connection with Allah by removing any form of idolatry or misplaced reverence, whether towards graves, saints, or other sacred objects. It encourages believers to understand the essence of Islamic worship and follow the authentic teachings of Prophet Muhammad (peace and blessings of Allah be upon him), urging them to focus on Allah as the sole object of worship and reliance.

Written in simple language, The Fortification of Faith has been influential in Islamic reform movements and continues to inspire those who seek to purify their faith in line with the principles of Tawhid.