According to Jacob ben Asher and
Isaac Aboab I, Barukh she-Amar is described by the
Sefer Hekhalot. However, no extant manuscript contains this reference.
Moses ben Jacob of Coucy,
Amram ben Sheshna,
Natronai ben Hilai, and
Saadia Gaon attest to its popular use by the
9th century. According to the
Mishneh Torah (), this prayer was instituted by the
Great Assembly; () claims "this is the best of the praises, because the Great Assembly did not establish it but rather was given to the wise tradents by way of a note from heaven." In the Sephardic and Mizrahi liturgies, as well as
Nusach Sefard, the custom is to recite most of the additional psalms of Shabbat (except for Psalms 92 and 93) prior to Barukh she-Amar on Shabbat. ==Aspects of God==