In his introduction The Sufis, a book Robert Graves co-wrote with Idries Shah, Graves translates a poem of the Sufi mystic Ibn Arabi (1165-1240) which illustrates a triple goddess as a theme among medieval Sufis:

I follow the religion of Love,
Now I am sometimes called
A Shepherd of gazelles
And now a Christian monk,
And now a Persian sage.
My beloved is three-
Three yet only one;
Many things appear as three,
Which are no more than one.
Give Her no name,
As if to limit one
At sight of Whom
All limitation is confounded.

In this book, Robert Graves and Idries Shah explore the influences that medieval Kabbalah and pre-Islamic Sufi beliefs had on surviving pre-Christian folk-traditions in Europe.