NonDuality - "Ein Sof" or infinite nothingness

According to Michaelson, nonduality begins to appear in the medieval Jewish textual tradition which peaked in   Hasidism : 

As a Jewish religious notion, nonduality begins to appear unambigously in Jewish texts during the medieval period, increasing in frequency in the centuries thereafter and peaking at the turn of the nineteenth century, with the advent of Hasidism. It is certainly possible that earlier Jewish texts may suggest nonduality – as, of course, they have been interpreted by traditional nondualists – 

Michaelson explores nonduality in the tradition of Judaism:

Judaism has within it a strong and very ancient mystical tradition that is deeply nondualistic. "Ein Sof" or infinite nothingness is considered the ground face of all that is. God is considered beyond all proposition or preconception. The physical world is seen as emanating from the nothingness as the many faces "partsufim" of god that are all a part of the sacred nothingness

From :   Everything is God, The Path of Nondual Judaism by Jay Michaelson