What did Khabbab say he observed to confirm that the Prophet Muhammad (saw) used to recite the Qur'an in the Zuhr and the `Asr prayers?
 Narrated Abu Ma`mar:                     I asked Khabbab whether the Prophet 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 that?" He said, "From the movement of his beard."