“Abu Ja‘far (a.s.), has said, ‘If a people perform Salah (prayer) and there is a space between them and the Imam, which cannot be covered by one step, that Imam is not their Imam. Any row which performs Salah (prayer) following an Imam and the space between this and the row in front is more than can be covered by one step it is not of that (row). If there is a barrier or wall in between, it is not a Salah (prayer) for them unless one is in front of a door.’ He (the narrator) has said that he (the Imam) said, ‘These arches did not exist in the time of anyone. The tyrants have invented them. Salah (prayer) of those who perform behind them, following those who perform inside is not valid Salah (prayer).’ Abu Ja‘far (a.s.), has said, ‘The rows must be complete, connected with each other and there must be a space of one step between two rows. The space must be of the length of human body that falls (when in Sajdah (prostration)).”’