What did Khabbab notice about the Prophet Muhammad (saw) when he recited his Zuhr and 'Asr prayers?
 Narrated Abu Ma`mar:                     We said to Khabbab "Did Allah's Apostle used to recite in Zuhr and `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."