COMMENTARY on 49:3
A. Yusuf Ali:

Translation:
Those that lower their voices in the presence of Allah's Messenger,- their hearts has Allah tested for piety: 4922 for them is Forgiveness and a great Reward.
Commentary:

4922  The essence of good manners arises from the heart. The man who really and sincerely respects his Leader has true piety in his heart, just as the man who does the opposite may undo the work of years by weakening the Leader's authority.