Salam,
Bismillah.
Bismillah.
Narrated Abu Ma'mar:
We asked Khabbab whether Allah's Apostle 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 about it?" He said, "By the movement of his beard."
- Dhuhr and `Asr are the sirri (silent/in which we whisper) prayers. Imaam does not recite aloud in congregation. Everyone recites their own surahs.
- How to know if someone is reciting something in the prayer or not? Check the movement of their beard (or lips). Which means, one should lip sync in Salah. Whisper to your Lord, per se. Don't just go about it in your heart/mind.
Wassalam.