Tzidkascha for the Death of Moshe

I saw it brought down that Moshe Rabbeinu died on Shabbos afternoon (one of the three tsadikim that died on Shabbos afternoon. Each of these Tsadikim – Moshe Yosef and Dovid – are keneged one of the pesukim in the Tzidkascha prayer on Shabbos.) However, the Torah also says that Moshe wrote twelve sifrei torah on the day of his death. How could Moshe write on Shabbos?

Answer:

This is a good question, and has already been asked by the Mordechai, in the laws of writing a Sefer Torah.

Another question, which is mentioned by Tosafos (Menachos 30) and the Rosh (Pesachim 105) is that the pasuk writes, citing from Moshe, “I am one hundred and twenty years old today.” If the day was Shabbos, how was this written?

Because of these questions, the rishonim suggest a different reason for the recitation of tziskascha, namely, that we perform tzidduk ha-din for the wicked who return to Gehinom after Shabbos.

The Bach (292), however, resolves the questions by suggesting that Moshe died on Friday afternoon, but his burial was on Shabbos, and we say tziskascha on account of his burial.

The Shelah (cited in Kehilos Yaakov Bava Kama 45) suggests that the writing was done by means of a Shem (not by human hands), and the Chasam Sofer (29) cites a creating answer from the Rama of Fano, namely that the day was only Shabbos from the Divine perspective, but not from the human perspective (the day of Shabbos was ‘lengthened’; the Chasam Sofer however rejects the approach).

For another answer see also Eliyah Rabba 292:15, and Korban Nesanel (Pesachim Chap. 10, no. 20).