Why does the Torah use the double Lashon "Shamor Tishm'run"?
Rashi: The Torah is issuing a stern warning to take steps not to forget one's learning. 1
Such as by constant revision. See also Ba'al ha'Turim.
What are the implications of "Shamor ... le'Ahavah es Hashem Elokeichem"?
Seforno: It implies that one should learn Torah in order to understand His Chasadim via which one cames to love Him.
What are the implications of "Laleches be'Chol Derachav"?
Rashi: 'Mah Hu Rachum, af Atah Rachum
How is it possible to cleave to Hakadosh-Baruch-Hu, who is described as 'a Consuming Fire'?
Ramban #1 (citing the Ibn Ezra): It means to love Hashem and to go in His ways in order to cleave to Him in the end. 3
Ramban #2: With reference to Avodah-Zarah, it entails constantly cleaving to Hashem in one's mind to the exclusion of all other deities.
Ramban #3: The Torah means that one's mind should constantly cleave to Hashem