Abu Amr al-Shaybani narrates from Sayyiduna Zayd bin Arqam (may Allah be pleased with him); he said: We used to talk during the prayer; one of us would speak to his brother about something he needed, until this verse was revealed: "Guard the prayers, especially the middle prayer, and stand before Allah in devout obedience" [al-Baqarah: 238], and we were then ordered to keep silent.
Hadith Referenceالمعجم الكبير للطبراني / باب الزاي / 5043