" إِذَا قُلْتَ لِصَاحِبِكَ أَنْصِتْ وَالإِمَامُ يَخْطُبُ فَقَدْ لَغَوْتَ "
It was narrated from Abu Hurairah that: The Messenger of Allah (ﷺ) said: "If you say to your companion: 'Be quiet and listen' when the imam is delivering the Khutbah, you have engaged in idle speech."