This error was detected by Menahem Lonzano, who, in his poem "Derek Ḥayyim" ("Shete Yadot," p. 122), expressly states that the ethical work in question belonged to Zerahiah.
Lonzano did not succeed, however, in correctly establishing the identity of its author, for a second error immediately arose.
The Sefer ha-Yashar is divided into eighteen short chapters,[2] and treats the ethical principles which underlie the relation of man to God.
It is an imitation of Bahya ibn Paquda's Hobot ha-Lebabot, which Zerahiah acknowledges in his preface that he had studied, although he found it too long and too profound for the average reader.
The indebtedness of the Sefer ha-Yashar to the "Hobot ha-Lebabot" is especially evident in the first chapter, entitled Sod Beri'at 'Olam, which is simply a brief summary of the chapters called Sha'ar ha-Yihud and Sha'ar ha-Behinah in Bahya's work.