Sayyiduna Abu Hurayrah (may Allah be pleased with him) said that the Prophet (peace and blessings be upon him) finished a prayer in which the recitation is aloud and said: "Who among you was reciting along with me in the prayer just now?" A man said: O Messenger of Allah, I was reciting. He (peace and blessings be upon him) said: "That is why I was thinking: what is the reason that reciting the Qur'an is becoming difficult for me?" From then on, people stopped reciting with the Messenger of Allah (peace and blessings be upon him) in the prayers in which the recitation is aloud.
Abu Dawud (may Allah have mercy on him) said that Ma'mar, Yunus and Usamah bin Zayd narrated this hadith of Ibn Ukaymah from al-Zuhri with the same meaning as the narration of Malik.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2892