كتاب الْمَسَاجِدِ وَمَوَاضِعِ الصَّلاَةِ
5  
The Book of Mosques and Places of Prayer
(7)
Chapter: The prohibition of speaking during the prayer, and the abrogation of its former permissibility
(7)
باب تَحْرِيمِ الْكَلاَمِ فِي الصَّلاَةِ وَنَسْخِ مَا كَانَ مِنْ إِبَاحَتِهِ ‏
Sahih Muslim 539 a

Zaid b. Arqam reported:

We used to talk while engaged in prayer and a person talked with a companion on his side in prayer till (this verse) was revealed:" And stand before Allah in devout obedience" (ii, 238) and we were commanded to observe silence (in prayer) and were forbidden to speak.
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا هُشَيْمٌ، عَنْ إِسْمَاعِيلَ بْنِ أَبِي خَالِدٍ، عَنِ الْحَارِثِ بْنِ شُبَيْلٍ، عَنْ أَبِي عَمْرٍو الشَّيْبَانِيِّ، عَنْ زَيْدِ بْنِ أَرْقَمَ، قَالَ كُنَّا نَتَكَلَّمُ فِي الصَّلاَةِ يُكَلِّمُ الرَّجُلُ صَاحِبَهُ وَهُوَ إِلَى جَنْبِهِ فِي الصَّلاَةِ حَتَّى نَزَلَتْ ‏{‏ وَقُومُوا لِلَّهِ قَانِتِينَ‏}‏ فَأُمِرْنَا بِالسُّكُوتِ وَنُهِينَا عَنِ الْكَلاَمِ ‏.‏
Reference : Sahih Muslim 539a
In-book reference : Book 5, Hadith 43
USC-MSA web (English) reference : Book 4, Hadith 1098
  (deprecated numbering scheme)