In summary, the Rambam does not mention “Yaakov,” nor does the 15th century Avudraham who lived in Spain. Yet, Rabbi Yechiel Bassan from Greece (16th century, in the period of the Maharit) tells us that Ashkenazim add “Yaakov” but Sephardim do not. He then informs us that in the Venetian siddurim published in the mid-16th century, the publishers take note of the Rivash’s objections but insist on mentioning “Yaakov” and cite a Zohar as support for their position against that of the Rivash. The Venetian publishers conclude that one should add the word Yaakov as it appears in all the early machzorim.
Most Ashkenazi machzorim that I have seen have the word “Yaakov” in parenthesis. But we find, for example, that the Baal “Yosef Ometz” (1570-1637) writes that the custom in Frankfurt is to add, “l’zaro shel Yaakov.” He also states, “One should not stray from the custom of the early, holy chazzanim of Frankfurt”
May Hashem remember us all in the great merits of all our holy fathers: Avraham, Yitzchak, and Yaakov.
Rabbi Yaakov Klass, rav of Congregation K’hal Bnei Matisyahu in Flatbush, Brooklyn, is Torah Editor of The Jewish Press. He can be contacted at firstname.lastname@example.org.