879. hadíth
وَ رَوَى عَنْهُ عَلَيْهِ اَلسَّلاَمُ زُرَارَةُ أَنَّهُ قَالَ: «إِذَا أُقِيمَتِ اَلصَّلاَةُ حَرُمَ اَلْكَلاَمُ عَلَى اَلْإِمَامِ وَ عَلَى أَهْلِ اَلْمَسْجِدِ إِلاَّ فِي تَقْدِيمِ إِمَامٍ »
Zurarah narrated from Imam Abu Ja'far (a.s) that He said: "When the iqamah (second call to prayer) is pronounced, speaking becomes prohibited for the Imam and the people of the mosque, except in the case of appointing an Imam."