פּירוש אויף במדבר 15:40

In order that you will remember. It already said, “And you will remember all of Hashem’s commandments.” This teaches that if you will remember you will be holy, and you will not become defiled by the heart’s desires, which pollute the intellect.

למען תזכרו, so that you would be free from thoughts of vain matters; once you are no longer concerned with the pursuit of the transient material allusions n this life, you will be receptive to the marvelous ways of the Torah, through the study of which you will come to recognise the greatness of the Creator and His amazing love for His creatures.

למען תזכרו ועשיתם את כל מצותי, “in order that you will remember and carry out all My commandments.” The Jerusalem Talmud Berachot 2,4, discussing the requirement to recite the קריאת שמע both mornings and evenings, explains that when reciting this verse the letter ז in the word תזכרו has to be drawn out somewhat when enunciated. The reason is to avoid that the word sounds like תשכרו, i.e. “you will secure compensation,” as one should not perform the commandments only in order to receive the reward promised (Avot,1,3). In this connection we may add that dwelling on that letter ז may also bring to mind the Torah which consists of 7 books (when we include the verses in Numbers 10,35-36 which were introduced by the inverted letters נ to show that the Book of Numbers are actually three books, giving us a total of seven Books of Moses). Seeing that the commandment of tzitzit is equal in moral weight to that of all the other commandments combined, such a thought when drawing out the letter ז is quite near at hand.
Another thought that may surface when we pronounce the letter ז in the word תזכרו as urged to do by the Jerusalem Talmud Berachot is that it conjures up thoughts of the שבת הגדול, the “great” Sabbath. The subject matter of the whole verse then is: “I have commanded you to perform this commandment involving the blue thread here on earth in order that corresponding to your activity on earth you will also remember that in the celestial regions there is an emanation which is part of the emanation הכל which is also known as the שבת הגדול. The words which follow, i.e. ועשיתם אותם, “and you will perform them,” mean that when you concentrate on these various meanings of the letter ז in the word תזכרו you will in effect be thinking of all the commandments.