I recently saw a beautiful thought from the Shelah HaKadosh.
But first, some background:
There are 620 letters in the Ten Commandments.
The commentaries point out that 620 is the numerical value of the word כתר- keter/crown, as in Keter Torah, the Crown of the Torah, and so there are 620 letters.
The rabbis further tell us that the number 620 corresponds to the 613 Mitzvot, plus the 7 rabbinical laws. These seven rabbinic mitzvot are: making a beracha before any pleasure, washing netilat yadayim, lighting Shabbat candles, putting up an Eruv, saying Hallel, and the holidays of Hanukah and Purim.
So the 620 letters in the Ten Commandments are meant to include the whole Torah, and also hint to the 613+7 Mitzvot.
That is all a standard explanation that I have heard in the past.
The Shelah adds a beautiful Hiddush:
He suggests examining the last seven letters of the Ten Commandments, which comprise the words אשר לרעך
That is to your friend
He explains that those let seven letters hint to the Mitzvah of Ve’Ahavta LeRe’echa Kamocha/ Loving your friend like you love yourself, which is the Klal Gadol B’Torah- the all-inclusive Mitzvah that includes the entire Torah. Therefore, he explains, with the Ten Commandments, Hashem hints to the 613 Mitzvot, plus an additional hint to what we should focus on: the all-inclusive Mitzvah of
Ve’Ahavta LeRe’echa Kamocha,
We should all look at life through that lens, because a person can’t possibly grab onto every little mitzvah, and have them all on his mind constantly. But with the Mitzvah of Ve’Ahavta LeRe’echa Kamocha, a person can hold onto the Torah, because many, many Mitzvot come from that Mitzvah, even Mitzvot between man and God. For example, if I have to be nice to my friend, surely I have to be nice to my Creator.
This is a beautiful concept.
אשר לרעך
Those last seven letters were put there in order to give us an all-inclusive approach to the Torah: Ve’Ahavta LeRe’echa Kamocha.
Have a wonderful day.