Narrated from him from al-Hasan from Zur’ah from Sama’ah, who said:
Abu Abdillah عليه السلام said: "When the mu’adhdhin gives the iqamah for the prayer, then speaking becomes prohibited, except if the people do not have a known imam."
Ali Akbar al-Ghaffari
Tahdhīb al-Aḥkām fī Sharḥ al-Muqniʿah, vol. 2, p. 60