Fortress of the Muslim (also Fortification of the Muslim; Arabic: حصن المسلم من أذكار الكتاب والسنة, ḥiṣn al-Muslim min ad͟hkār wa l-sunna) is a book of supplications and invocations (dua) compiled by the Saudi Islamic scholar Sa'id bin Ali bin Wahf Al-Qahtani in October 1988.

[1] Al-Qahtani received his doctorate from the College of the Fundamentals of Religion of the Imam Mohammad Ibn Saud Islamic University in Riyadh, which is considered to be a Wahhabi educational institution.

[2][4] Al-Qahtani put a lot of effort into presenting the dua in his book as the true and pure record of the Quran and the most sound of ahadith, which is typical for Salafi authors.

[2] Fortress is very popular both among mainstream and Salafi Muslims, both recent converts and people born into ummah; they carry it with them and often try to memorise pages from it.

[9] By sponsoring the distribution of Fortress, they make sure that the believers recite the "correct" dua and not the customary ones, which may include asking the spirits of the ancestors for help – a practice seen as sinful by modernists.