Who wrote Sefer Yetzira?[1] Sefer Yetzira was written by Avraham Avinu. __________________________________________________________________ [1] Shlah Derech Chaim Parshas Vayeishev; Tocheches Mussar 57; Chida in Shem Hagedolim Samech 54 in name of Zohar Chadash Yisro p. 60; Kuzari Mamar 4; Ramak in end of his commentary on Sefer Yetzira; Yalkut Reuveini Lech
[1] Shlah Derech Chaim Parshas Vayeishev; Tocheches Mussar 57; Chida in Shem Hagedolim Samech 54 in name of Zohar Chadash Yisro p. 60; Kuzari Mamar 4; Ramak in end of his commentary on Sefer Yetzira; Yalkut Reuveini Lech Lecha; See Rambam Hilchos Avoda Zara 1/3 “Avraham wrote Sefarim regarding the Ikkur Hagadol of belief in Hashem”