אם לא תשמור לעשות את כל דברי התורה הזאת הכתובים בספר הזה ליראה את השם הנכבד והנורא הזה, "if you will not observe to carry out all the words of this Torah which have been written in this Book, in order for you to revere His honored and awesome name.⁠" The meaning of this verse is that there must be one overriding consideration running throughout all the commandments of the Torah, i.e. to infuse reverence in the people for the Lord. This is not the first time that Moses explains this as the overall purpose of Torah legislation. He had already made this point in Exodus 20,17 during the revelation at Mount Sinai, when he said: "God has come in order to test you and to ensure that the awe of Him shall be on your faces so that you shall not sin.⁠" King Solomon also concluded his Book of Proverbs with the need for יראת ה', "reverence and awe of the Lord" (Proverbs 31,30). We also find that Isaiah 33,6 emphasizes the need for this important virtue. Our sages, in elaborating on this theme in Shabbat 31, imply that even if one has studied all the tractates of the oral Torah, the yardstick by which man is measured after death is whether he did relate to all of this with reverence for the Lord or not.
The plain meaning of the verse in Isaiah 33,6 יראת ה' היא אוצרו is that it is a virtue stored up in God's treasury, something very dear to Him, consisting of the cumulative virtues of awe of Him by God-fearing people which God treats like a most precious possession, "locking it away" in His most inaccessible treasure chamber. The reason that the prophet employs the term "treasure, something to be stored,⁠" in connection with this virtue is that a king cannot establish a treasury unless he collected the funds for it from outsiders, from people. Anything the king locks away is called אוצר, "treasure.⁠" What all this teaches is that of all the virtues we must acquire, a measure of awe and reverence of the Lord is the overriding virtue, "coloring,⁠" i.e. lending value, to all the other virtues man practices. One of the reasons that this is so is that all the other commandments can be performed only at certain times, such as the wearing of a tallit or phylacteries. When one has put on these phylacteries one has effectively concluded performing this mitzvah. Not so with the commandment to relate to the Lord with יראה, with awe. It is a commandment which permeates all our waking hours. This is what David had in mind when he wrote (Psalms 19,10) "the reverence for the Lord is pure and endures forever.⁠" Such a statement could not have been made concerning performance of any of the other commandments which require active performance, [as opposed to the mark of circumcision on our flesh. Ed.] It is a commandment which is both positive and negative, i.e. cultivating it is the positive aspect of the commandment, whereas failure to cultivate it and to maintain it at all times is a violation of it, i.e. equivalent to transgressing a negative commandment.