Imam Muhammed al-Baqir (AS) has said:
"Surely the book of Allah is the most truthful of all narrations, and the best of all stories, and Allah (SWT) says: 'And when the Quran is being recited, then listen to it and remain silent, that mercy may be shown to you.' [Suratul A'raaf, verse 204] "
Usool-e-Kaafi Vol. 3, Page 422