Sahih al-Bukhari, Volume 1, Book 12, Hadith 727 (USC-MSA) ⓘ

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."

حَدَّثَنَا عُمَرُ بْنُ حَفْصٍ، قَالَ حَدَّثَنَا أَبِي قَالَ، حَدَّثَنَا الأَعْمَشُ، حَدَّثَنِي عُمَارَةُ، عَنْ أَبِي مَعْمَرٍ، قَالَ سَأَلْنَا خَبَّابًا أَكَانَ النَّبِيُّ صلى الله عليه وسلم يَقْرَأُ فِي الظُّهْرِ وَالْعَصْرِ قَالَ نَعَمْ‏.‏ قُلْنَا بِأَىِّ شَىْءٍ كُنْتُمْ تَعْرِفُونَ قَالَ بِاضْطِرَابِ لِحْيَتِهِ‏.‏