Abu Wa'il narrates: A man came to Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) and said: "O Abu Abd al-Rahman, should I recite behind the imam?" He said: "Remain silent for the Qur'an (being recited), for in prayer there is preoccupation, and the imam will suffice for you."
Al-Tabarani recorded it in al-Mu'jam al-Kabir and al-Mu'jam al-Awsat, and its narrators have been declared trustworthy.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2647