What did Khabbab bin Al-Art observe while the Prophet Muhammad (saw) recited the Qur'an during Zuhr and 'Asr prayers?
 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."