Asim al-Ahwal عاصم الأحول · The Book of Forgetfulness (In Prayer)

"We used to speak to each other during the prayer, saying whatever was necessary, at the time of the Messenger of Allah (ﷺ), until this verse was revealed: Guard strictly (five obligatory) As-Salawat (the prayers) especially the middle Salah (i.e. the best prayer- 'Asr). And stand before Allah with obedience (and do not speak to others during the Salah (prayers)), so we were commanded to be silent."

"The Messenger of Allah (ﷺ) commanded me to recite Al-Mu'awwidhat following every prayer."