These verses announce the commandments that follow and give the reason for obeying them: God"s blessing. God"s blessing would come in the form of long life, peace and prosperity, and numerous descendants. The "fear" of God ( Deuteronomy 6:2; cf. Deuteronomy 5:29, 35 ( Deuteronomy 6:2); et al.) is the respect that comes from an appreciation of His character. [source][source][source]
"It is a fear that produces not obeisance but obedience, not worry but worship ( Deuteronomy 6:13)." [1][source]
"Israel"s continued enjoyment of a habitation in God"s land, like Adam"s continued enjoyment of the original paradise, depended on continued fidelity to the Lord." [2][source]