Characteristics of Prayer

Bukhari :: Book 1 :: Volume 12 :: Hadith 728

Narrated Abu Ma'mar:

I asked Khabbab bin Al-Art whether the Prophet used to recite the Qur'an in the Zuhr and the 'Asr prayers. He replied in the affirmative. I said, "How did you come to know that?" He replied, "From the movement of his beard."