זוהר שמות — דף קסד ע”ב

When the people of Israel come to the synagogue and pray together, this is the glory of the King, for all the celestial camps adorn themselves accordingly. Even ten people suffice to complete this perfect tiqqun, since the entire configuration of that King is in ten. When Israel below does not come to pray, all the holy celestial camps are broken from their proper arrangement, as praises cannot ascend fittingly. The Tabernacle of Moses had ten curtains corresponding to ten heavens, with the Shekhinah standing above them all, beyond the count.