Sahih al-Bukhari 1200
Sahih al-Bukhari · Book 21: Actions while Praying · What speech is prohibited during As-Salat
Narrated Zaid bin Arqam:
حَدَّثَنَا إِبْرَاهِيمُ بْنُ مُوسَى ، أَخْبَرَنَا عِيسَى ـ هُوَ ابْنُ يُونُسَ ـ عَنْ إِسْمَاعِيلَ ، عَنِ الْحَارِثِ بْنِ شُبَيْلٍ ، عَنْ أَبِي عَمْرٍو الشَّيْبَانِيِّ ، قَالَ قَالَ لِي زَيْدُ بْنُ أَرْقَمَ إِنْ كُنَّا لَنَتَكَلَّمُ فِي الصَّلاَةِ عَلَى عَهْدِ النَّبِيِّ صلى الله عليه وسلم، يُكَلِّمُ أَحَدُنَا صَاحِبَهُ بِحَاجَتِهِ حَتَّى نَزَلَتْ {حَافِظُوا عَلَى الصَّلَوَاتِ} الآيَةَ، فَأُمِرْنَا بِالسُّكُوتِ.
In the lifetime of the Prophet (ﷺ) we used to speak while praying, and one of us would tell his needs to his companions, till the verse, 'Guard strictly your prayers (2.238) was revealed. After that we were ordered to remain silent while praying.