Tafsiran Bilangan 15:40: Midrash Lekach Tov, Sforno, Rabbeinu Bahya & Rav Hirsch

The verse: In order that you will remember and do them - to make remembering like action. Great is remembering, as it is stated (Malachi 3:22), "Remember the Torah of Moshe, My servant." And it states (Jeremiah 51:50), "remember the Lord from afar (all the corners of the world)." And it states (Isaiah 44:21), "Remember these things, Yaakov." And do all of My commandments - this teaches that remembering brings to action. And you shall be holy to your God - this is the holiness of tzitzit (fringes). It is saying that tzitzit adds holiness to the Jewish people. It is written three times: "and they shall make for themselves tzitzit; and they shall place on the tzitzit; and they shall be for (le) tzitzit." When you divide the [numerical count of the letter,] lamed (which is 30 and spells le) - ten for one, ten for one and ten for one - all of them become fully spelled. For they are all written tzitzat, without [a letter,] yod (the numerical count of which is ten). Rabbi Chanina ben Antigonos said, "What does it state about anyone who fulfills the commandment of tzitzit? 'In those days, ten people from nations of every tongue will take hold; they will take hold of every Jew by a corner of their cloak' (Zechariah 8:23) - this teaches that in the future, every Jew will be served by 2,800 servants.

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.