Sahih al-Bukhari 760
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · The recitation of the Qur'an in a Zuhr prayer
Narrated Abu Ma`mar:
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.
I asked Khabbab whether the Prophet (ﷺ) 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."