What is "bahir"

Bahir or Sefer HaBahir ( Hebrew: סֵפֶר הַבָּהִיר, "Book of the Brightness") is an anonymous mystical work, attributed to a 1st-century rabbinic sage Nehunya ben HaKanah (a contemporary of Yochanan ben Zakai) because it begins with the words, "R. Nehunya ben HaKanah said". It is also known as Midrash of Rabbi Nehunya ben HaKanah מִדְרָשׁ רַבִּי נְחוּנְיָא בֶּן הַקָּנָה.

It is an early work of esoteric Jewish mysticism which eventually became known as Kabbalah.