פּירוש אויף דברים 26:16

“The Lord your God commands you this day to observe” [26:16]. Even though the Holy One said this forty years after the time that the Holy One had given the Torah, and now says, I have given you the Torah, because He wants to teach us and show that the person should always have his thoughts as if he had just received the Torah now. It is so beloved by the person that he thinks it is something new and he must write down the Torah, because the people will forget the giving of the Torah. Therefore, the Holy One says, he should think that he received the Torah today. The verse began with “this day” and ends “with all your soul” [26:16]. This shows us that the person should risk his life for the Torah, just like at Mount Sinai, there was great fire, lightning and thunder, nonetheless Israel stood and wanted to hear the words of the Holy One.¹¹Bahya, Deuteronomy, 26:16.

היום הזה ה׳ אלהיך מצוך THIS DAY THE LORD THY GOD COMMANDETH THEE — This suggests: each day they (God’s commandments) should be to you as something new (not antiquated and something of which you have become tired), as though you had received the commands that very day for the first time (Midrash Tanchuma, Ki Tavo 1; cf. Rashi on Deuteronomy 11:13).

The words on this day mark the resumption of Moshe’s speech.