(a) Awn bin Musa (may Allah have mercy on him) said: I heard Mu'awiyah bin Qurrah (may Allah have mercy on him) say that people used to talk and the like during prayer, so Allah Almighty revealed this blessed verse: "When the Qur'an is recited, listen to it attentively and remain silent." [Surah al-A'raf: 204]
(b) Sa'id bin Mansur narrated this hadith from Awn and added in it: "So the storytellers applied it to their storytelling."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2888