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."
Hadith Referenceصحيح البخاري / كتاب الأذان (صفة الصلوة) / 777
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة