Messenger of Allah ﷺ said, "When the Imam is delivering the Khutba, and you ask your companion to keep quiet and listen, then no doubt you have done an evil act." (Using translation from Bukhārī 934)
أَخْبَرَهُ أَنَّ رَسُولَ اللهِ ﷺ قَالَ إِذَا قُلْتَ لِصَاحِبِكَ أَنْصِتْ يَوْمَ الْجُمُعَةِ فَقَدْ لَغَوْتَ