In a book I’m reading I encountered a quote from a highly fragmentary text from Qumran that is usually known as 4QInstruction. The fragment 4Q417 includes the words “for engraved are the ordinances of God, about all the [iniquities of the] sons of Seth, and a book of memorial is written before him”. [The picture on the right is not of 4QInstruction, lest anyone enlarge it and be disappointed - I couldn't find an image of this particular text online].
In later times, including among the Mandaeans but also in texts from Nag Hammadi, certain Gnostics would trace their teaching back to Seth and to wisdom that he inscribed on stele.
There is significant uncertainty about how the fragment mentioned above is to be positioned relative to other fragments that seem to be part of the same work. Also uncertain is whether this is a work of the Qumran sectarians themselves or simply a work that is part of their collection.
Although the idea of a righteous race descended from Seth does not seem to have been at all limited to groups that can be categorized as Gnostics, it is still intriguing that the text from Qumran appears to polemicize against the sons of Seth. And so this is a text that definitely merits further investigation by those interested in tracing the history of the “Sethian” ideas that became part of the heritage of later Mandaeans and other “Gnostics”.