Rashi on Deuteronomy 11:22/רש"י על דברים י״א:כ״ב

1שמר תשמרון [IF] YE SHALL DILIGENTLY OBSERVE [ALL THESE COMMANDMENTS] — The repetition of the verb implies an admonition to be very much on one’s guard: to be careful in respect to one’s study of the Torah that it should not be forgotten (cf. Sifrei Devarim 48:2).

2ללכת בכל דרכיו TO WALK IN ALL HIS WAYS — He is merciful, be thou merciful; He bestows lovingkindness, bestow thou lovingkindness (Sifrei Devarim 49:1).

3ולדבקה בו AND TO CLEAVE TO HIM — Is it possible to say this? Is He not “a consuming fire” (Deuteronomy 4:24)? But it means: cleave to the scholars and sages, and I will account it unto you as though you cleave to Him (Sifrei Devarim 49:2).