Sefat Emet, Deuteronomy, Vaetchanan 8/שפת אמת·דברים·ואתחנן ח׳

3In the verse (Deut. 5:19), "And these words Adonai spoke to all of your congregation," "all" seems to be superfluous. One must say that [this refers] to all congregations, where Jews gather any time, as the Sages said (Avot 3:6), "When ten gather and there are words of Torah, the Shechinah rests among them." And all this comes at the time of the Giving of the Torah, as it says (Deut. 4:10), "Gather [the people to Me} that I may let them hear My words" -- a foundation and illumination that all gatherings of Jews throughout the generations can awaken those words, as it says, "a loud voice, that did not yasaf" -- that did not cease. And just as the ten speeches are the foundation and structure for all of Creation, so the Ten Sayings are the foundation and structure for all of Jews' conduct. The only difference is that the speeches were solely from the will of the Creator, but the Sayings were from the preparation of the Israelites, who preceded "We will do" [before "we will hear."] and self-sacrifice for the glory of His name. And therefore, even now this power is aroused through preparation down below. And similarly, through an individual soul, when the person gathers all force to be subservient to Him, that person is in the category of "all of your congregation," and so it says (Avot 3:2), "Even if one person sits and studies, [there is a reward]."