This piyyut has been preserved in two manuscripts, Oxford 2852/8 (fol. 40b) and Adler 2038 (fol. 5b),
which provide slightly different readings. Both MSS give the dates as the 23rd of Shevat.
The Adler MS, which is preferred by Margaliot, mentions the
fast of the Ra'ash Shevi'it on the 23rd (day) of it ( = Shevat)
.
The Oxford version names the earthquake Ra'ash Shevi`i.
Margaliot bases himself on the version of the Adler manuscript,
thus interpreting the term Ra'ash Shevi'it as the
earthquake of the sabbatical (= seventh) year
(Shemittah:
Deut. 15).
