Characteristics of Prayer

Bukhari :: Book 1 :: Volume 12 :: Hadith 713

Narrated Abu Ma'mar:

We asked Khabbab whether Allah's Apostle used to recite (the Qur'an) in the Zuhr and the 'Asr prayers. He replied in the affirmative. We said, "How did you come to know about it?" He said, "By the movement of his beard."