— But I still would say: If Kadesh li and Vehaya ki yeviacha, which were preceded by other mitzvoth are included in "binding," then the Ten Commandments, which were not preceded by other mitzvoth, how much more so should they be included in "binding"! — You say "a fortiori"? Now if Vayomer, which is included in "repetition," is not included in "binding," then the Ten Commandments, which are not included in "repetition," how much more so should they not be included in "binding"! — No, this is refuted by Kadesh li and Vehaya ki yeviacha, which, though they are not included in "repetition," are included in "binding." It is, therefore, written "And you shall bind them." These (the aforementioned) are included in "binding," and not the Ten Commandments.
Are the Ten Commandments Included in the Tefillin
Sifrei Devarim 35:2