(Imām Bukhārī narrates): Qutaibah ibn Sa'īd narrated to us, he said: Jarīr narrated to us, from al-A'mash, from 'Umārah ibn 'Umair, from Abī Ma'mar, he narrates that:
I asked Khabbāb, may Allāh be pleased with him: Did the Messenger of Allāh ﷺ recite the Qur'ān in Zuhr and 'Asr? He said: Yes. We asked: How did you know? He said: By the movement of his beard.
Reference: Sahih Al Bukhari 777