Sharḥ Muslim; and I shall cite his exact words later under the heading, “The textual evidence that the sunnah is to perform the prayer in the musalla.”
Up to this very day, by Allah’s grace, this sunnah is still observed in many Muslim lands—Damascus, Jordan, Egypt, Algeria, Pakistan, and others.
What need, then, is there to split the worshippers among the countless mosques—large and small—scattered everywhere, some of them so close that only fifty steps, or even less, separate one from another?
Had those writers confined their claim to performing the prayer in a single, largest mosque, they would have had a precedent for that view, as will be shown from Imām al-Shāfiʿī, may Allah have mercy on him. But they feel no shame in attributing to the early Muslims what none of them ever asserted, merely to fight against the sunnah.
In fact, all Muslims agree that praying in the musalla is the sunnah when the mosque cannot hold the congregation, and the majority go further and say: even if the mosque were spacious enough, anyone who abandons the musalla has, through his ignorance, acted in clear contravention.