It is well known that ritual purity is an essential element in Islamic religious practice and that it holds great importance in many Muslims’ daily lives. In premodern Muslim societies, the same standards of ritual purity were also important to specific magical practices and the uses of that magic. This paper will demonstrate that, according to the earliest available evidence, the maintenance of ritual purity was consistently connected with Islamic forms and beneficial ends throughout the Middle Ages, while conversely the neglect of purity—or its deliberate violation—was connected with much more sinister forms of magic. One major resource will be the Fihrist of Ibn al-Nadim. This text describes the full scope of Arabic literature in tenth century Baghdad, including many different kinds of occult writings. In particular, Ibn al-Nadim explained that in practicing “blameworthy magic” a magician deliberately violated Islamic norms of ritual purity in order to please evil spirits, that they might do the magician’s bidding. Furthermore, such magic was used primarily to harm. On the other hand, Ibn al-Nadim explained that practitioners of the “praiseworthy” system commanded spirits because those magicians knew the names of God and other holy secrets—and also because these practitioners scrupulously observed all Islamic norms of ritual purity and ethical behavior. While the specific works described by Ibn al-Nadim do not survive, similar approaches can be seen in surviving grimoires from later eras. For example, the corpus attributed to the thirteenth century Sufi Ahmad ibn Ali al-Buni strongly resemble Ibn al-Nadim’s description of the “praiseworthy” system: al-Buni’s works are mostly concerned with the special powers of Islamic symbols such as the Ninety-Nine Beautiful Names of God, the Greatest Name of God, verses of the Qur’an, and even letters of the Arabic alphabet. Furthermore, in its instructions al-Buni’s corpus places great emphasis on the importance of Islamic ritual purity and also on the need to use the great power of these Islamic symbols solely for beneficial ends.