Surah Al-A'raf Ayah 204

So, when the Qur'an is recited, listen to it, and be silent that you may receive mercy (204)

The Order to listen to the Qur'an

After Allah mentioned that this Qur'an is a clear evidence, guidance and mercy for mankind, He commanded that one listen to the Qur'an when it is recited, in respect and honor of the Qur'an. This is to the contrary of the practice of the pagans of Quraysh, who said,

لَا تَسْمَعُوا لِهَٰذَا الْقُرْآنِ وَالْغَوْا فِيهِ

("Listen not to this Qur'an, and make noise in the midst of its (recitation)")[41:26].

Ibn Jarir reported that Ibn Mas'ud said; "We would give Salams to each other during Salah. So the Ayah of Qur'an was revealed;

وَإِذَا قُرِئَ الْقُرْآنُ فَاسْتَمِعُوا لَهُ

(When the Qur'an is recited, then listen to it.)