Bahir or Sefer HaBahir (Hebrew: סֵפֶר הַבָּהִיר, Hebrew pronunciation: [ˈsefeʁ ˌ(h)abaˈ(h)iʁ]; "Book of Clarity" or "Book of Illumination") 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.
First mentioned in late 12th-century Languedoc/Provencal works, the Bahir is an early work of the esoteric Jewish mystical tradition that eventually became known as Kabbalah. The work is considered by scholars to be pseudepigraphical, composed in Provence in the late 12th century.