(a) It is narrated from Abu Wa'il that a man asked Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) about reciting behind the imam. He said: Remain silent for (listening to) the Qur'an, for in prayer there is enough to occupy you, and the imam's recitation is sufficient for you.
(b) "Remain silent for the Qur'an" is said when the Qur'an is being heard, not when it is not being heard. (That is, in loud recitation a person can hear it, but not in the silent prayers.)
(c) Alqamah said: I prayed beside Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him), and I did not know that he was reciting until he recited a verse of Surah Ta-Ha aloud (which I heard), namely: "And say: My Lord, increase me in knowledge." [Surah Ta-Ha: 114]
(d) It has been narrated to us through Abdullah bin Ziyad al-Asadi that he said: I stood beside Abdullah bin Mas'ud (may Allah be pleased with him) and prayed behind the imam, and I heard him reciting in Zuhr and Asr (behind the imam).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2900