Halakhah su Deuteronomio 31:19

Taz, Yoreh De'ah 270:4, concedes that Perishah's understanding of Rosh's position is entirely compatible with the text but declares that Bet Yosef's analysis must nevertheless be correct "for how can the commandment 'And now write unto yourselves' be abrogated with the passing of generations?" For that matter, Taz' objection may be raised with regard to Bet Yosef's interpretation as well. The biblical commandment is couched in the words "And now write unto yourselves this song" (Deuteronomy 31:19). The term "song" (shirah) is understood as referring to the Pentateuch. If so, the mizvah is clearly defined as requiring the copying of a specific text referred to as "this song." How, then, is it possible for this term, "with the passing of generations," to come to denote much more than the text of the Sefer Torah?

The difficulties associated with the position of Rabbenu Asher may be resolved if it is assumed that this authority translated the term "song" as denoting literally the Torah in its entirety. Indeed, the Gemara in three instances, Hagigah 12b, Nedarim 38a and Hullin 13b, clearly interprets the word "song", both in this and in other contexts, as a reference to the Pentateuch in its entirety.¹For an illuminating explanation of why the Torah is termed a “song” see R. Naphtali Zevi Yehudah Berlin, Ha‘amek Davar, Introduction. Thus, according to Rosh, a literal reading of Deuteronomy 31:19, yields an obligation to transcribe the full text of the Pentateuch.

However, the term "song", interpreted as meaning Torah, is not limited to denotation of the Written Law exclusively. Megillat Ta'anit, chapter 4, presents a highly significant interpretation of the concluding phrase of this very verse, "and teach it to the children of Israel, place it in their mouths." Megillat Ta'anit explains that the phrases "teach it to the children of Israel" and "place it in their mouths" are not at all synonymous expressions. Rather, "teach it" refers to the "song" of the immediately preceding phrase, i.e., the Written Law, while the phrase "place it in their mouths" is understood as a reference to the Oral Law which must be "placed in the mouth" since it may only be transmitted orally.²Cf., R. Yitzchak Ze’ev Soloveitchik, Ḥiddushei Maran Riz ha-Levi al ha-Torah (Jerusalem, 5723), p. 16a. See also the commentary of Ba‘al ha-Turim, Deuteronomy 31:19.