“The magic as displayed in Filāha coincides with the common Near Eastern patterns and is in this sense genuine: whether the exact procedures were used by the pagan population —either in the tenth century or earlier, if we agree with Fahd—is another question.
The Aramaic prayers would perhaps seem genuine, but when strongly Neoplatonic formulae occur in the invocations, one may doubt whether the peasants indeed used these prayers. It may be that the material is partly descriptive, describing the religious practices of the rural population, partly prescriptive, i.e. composed by the author, following pre-existing patterns, to invent new formulae.
It may strike many as surprising that there could have been rites like burnt offerings to Zuhal in the countryside, sqwād, of Iraq until the tenth century —if we accept a late date for the Nabatean corpus— but the evidence from Harrān makes this not unprecedented, and the magical procedures throughout history have always retained archaic religious material.
Likewise, the mere existence of Mandaeans shows the tolerance of Islam towards ultimately pagan religions. Had someone translated the Mandaean books into Arabic in the tenth century and circulated them outside the community, the texts would have been just as incongruent with the surrounding Islamic society as the books of the Nabatean corpus.
As the main texts of the Nabatean corpus purport to be translations of old manuscripts, the dating of the religious material in them, if it mirrors real procedures, is of course problematic. But in some cases, like when speaking about the lamentations over Tammūz, Ibn Wahshiyya speaks as himself, adding a translator’s note to the main text.
Thus, at least the pagan rites described in these passages were being performed in the early tenth century.
Although ignored by compilers of biographical dictionaries, Ibn Wahshiyya was much respected by those interested in magic, esoterica and the Nabatean or Sabian inheritance.
Not only was his main work, Filāha, excerpted by persons such as the author of the Arabic Picatrix (Ghāyat al-hakīm) ([pseudo]-al-Majrītī) and later writers of agricultural works —the latter, though, usually showed little interest for the religious and magical material in the work— but he was also profusely used by Maimonides in his Dalāla, from which source, together with Picatrix, the magic of the Nabateans and the Chaldaeans was transmitted into European languages.
Thus, through Ibn Wahshiyya, the magic of the Nabateans diffused throughout the civilized world, and Ibn Wahshiyya became an important link in the world history of magic and esoterica.”
Jaakko Hāmeem-Anttila, “Ibn Wahshiyya and Magic,” Anaquel de Estudios Árabes X, 1999, pp. 47-8.