وَإِذَا خَرَجَ الْإِمَامُ يَوْمَ الْجُمُعَةِ: تَرَكَ النَّاسُ الصَّلَاةَ وَالْكَلَامَ، حَتَّى يَفْرُغَ مِنْ خُطْبَتِهِ،
Translation: When the imam appears on Friday, people cease praying and talking until the khutbah is completed.
Attentive listening belongs to the public Friday rite. The ruling given here begins the restraint as the imam emerges; its starting point is discussed differently by the two students.