Nearby ayahs help place verse 49:1 in sequence and meaning.
يَـٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوا۟ لَا تَرْفَعُوٓا۟ أَصْوَٰتَكُمْ فَوْقَ صَوْتِ ٱلنَّبِىِّ وَلَا تَجْهَرُوا۟ لَهُۥ بِٱلْقَوْلِ كَجَهْرِ بَعْضِكُمْ لِبَعْضٍ أَن تَحْبَطَ أَعْمَـٰلُكُمْ وَأَنتُمْ لَا تَشْعُرُونَ
O you who have believed, do not raise your voices above the voice of the Prophet or be loud to him in speech like the loudness of some of you to others, lest your deeds become worthless while you perceive not.
إِنَّ ٱلَّذِينَ يَغُضُّونَ أَصْوَٰتَهُمْ عِندَ رَسُولِ ٱللَّهِ أُو۟لَـٰٓئِكَ ٱلَّذِينَ ٱمْتَحَنَ ٱللَّهُ قُلُوبَهُمْ لِلتَّقْوَىٰ ۚ لَهُم مَّغْفِرَةٌ وَأَجْرٌ عَظِيمٌ
Indeed, those who lower their voices before the Messenger of Allah - they are the ones whose hearts Allah has tested for righteousness. For them is forgiveness and great reward.