It is narrated from Abu Ma'mar that he said: We asked Sayyiduna Khabbab (may Allah be pleased with him): Did the Messenger of Allah (peace and blessings be upon him) recite in the Zuhr and Asr prayers? He said: Yes. We asked: How did you come to know that? He said: By the movement of his (peace and blessings be upon him) blessed beard.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2362