The Shechina rests on ten Jews:[1]

When ten Jews are gathered together the Shechina dwells upon them even if they are not involved in the learning of Torah, [so long as they are not transgressing any sin in their gathering, not even the sin of Bittul Torah[2]]. All the more so is the Shechina revealed when a Minyan of Jews are involved in the study of Torah or performance of a Mitzvah. This revelation is a great radiation of Hashem’s light and is without limit or end. Accordingly, it is unable to be invested within the soul or in the mind of those participating in the Minyan, and rather encompasses the person from head to toe. It is for this reason that one does not experience the great pleasure and pleasantness of the infinite light of the Shechina that is residing amongst us in the Minyan. It is not possible to experience the greatness of this revelation while the soul is within the body. [Furthermore, even the Mazal/root of the soul in Heaven does not experience this revelation, and hence the people of the Minyan are completely oblivious as to its visitation.[3]] If an angel were to be present in the area of this revelation that occurs in the presence of a Minyan, it would be filled with such fear and fright that it would cease to exist.

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[1] Tanya Igeres Hakodesh Epistle 23

[2] Rebbe in talk with Rav Mordechai Eliyahu

[3] Footnote of Rebbe in lessons in Tanya ibid