I observed prayer along with the Messenger of Allah ﷺ and with Abu Bakr, Umar and Uthman (may Allah be pleased with all of them), but I never heard any one of them reciting Bismillah-ir-Rahman-ir-Rahim loudly.  

صَلَّيْتُ مَعَ رَسُولِ اللَّهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ فَلَمْ أَسْمَعْ أَحَدًا مِنْهُمْ يَقْرَأُ {بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ}  

"I prayed behind the Messenger of Allah ﷺ, Abu Bakr, Umar and Uthman, may Allah be pleased with them, and I did not hear any of them say out loud: In the Name of Allah, The Most Gracious, The Most Merciful."  

صَلَّيْتُ خَلْفَ رَسُولِ اللَّهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ ؓ فَلَمْ أَسْمَعْ أَحَدًا مِنْهُمْ يَجْهَرُ بِ { بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ }  

[Machine] I prayed with the Messenger of Allah ﷺ , Abu Bakr, and Umar, and they did not recite aloud "Bismillah ir-Rahman ir-Rahim" (In the name of Allah, the Most Gracious, the Most Merciful) [Al-Fatihah 1].  

صَلَّيْتُ مَعَ رَسُولِ اللهِ ﷺ وَمَعَ أَبِي بَكْرٍ وَمَعَ عُمَرَ فَلَمْ يَجْهَرُوا بِ {بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ} [الفاتحة 1]  

I observed prayer along with the Messenger of Allah ﷺ and with Abu Bakr, Umar and Uthman (may Allah be pleased with all of them), but I never heard any one of them reciting Bismillah-ir-Rahman-ir-Rahim loudly. (Using translation from Muslim 399a)  

صَلَّيْتُ مَعَ رَسُولِ اللهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ فَلَمْ أَسْمَعْ أَحَدًا مِنْهُمْ يَقُولُ {بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ} [الفاتحة 1]  

[Machine] "I prayed behind the Messenger of Allah ﷺ , as well as behind Abu Bakr, Umar, and Uthman, and they would not audibly recite 'In the name of Allah, the Most Gracious, the Most Merciful' (Bismillah Ar-Rahman Ar-Raheem) in Surah Al-Fatiha."  

صَلَّيْتُ خَلْفَ رَسُولِ اللهِ ﷺ وَخَلْفَ أَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ فَكَانُوا لَا يَجْهَرُونَ بِ {بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ} [الفاتحة 1]  

[Machine] "I prayed behind the Messenger of Allah ﷺ , and behind Abu Bakr, Umar, and Uthman. They would not recite aloud the Bismillahir Rahmanir Rahim (In the name of Allah, the Most Gracious, the Most Merciful) in Al-Fatiha (Chapter 1)."  

صَلَّيْتُ خَلْفَ رَسُولِ اللهِ ﷺ وَخَلْفَ أَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ فَكَانُوا لَا يَجْهَرُونَ بِ {بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ} [الفاتحة 1]  

[Machine] One of us heard someone saying "In the name of Allah, the Most Gracious, the Most Merciful" and he says "Eehee Eehee, I have prayed behind the Messenger of Allah ﷺ, Abu Bakr, and Umar, and I did not hear any of them saying "In the name of Allah, the Most Gracious, the Most Merciful."  

سَمِعَ أَحَدًا مِنَّا يَقُولُ بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ يَقُولُ إِهِي إِهِي صَلَّيْتُ خَلْفَ رَسُولِ اللهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ فَلَمْ أَسْمَعْ أَحَدًا مِنْهُمْ يَقُولُ بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ  

[Machine] "And the Messenger of Allah ﷺ , Abu Bakr, and Umar, may Allah be pleased with them, did not utter aloud 'In the name of Allah, the Most Gracious, the Most Merciful.'"  

«وَكَانَ رَسُولِ اللَّهِ ﷺ وَأَبُو بَكْرٍ وَعُمَرُ رِضْوَانُ اللَّهِ عَلَيْهِمَا لَا يَجْهَرُونَ بِ {بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ} »  

[Machine] "This is our prayer with the Messenger of Allah ﷺ and Abu Bakr and Umar, may Allah be pleased with them. When Umar was martyred, Uthman took charge of it, may Allah be pleased with him."  

«هَذِهِ صَلَاتُنَا مَعَ رَسُولِ اللَّهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ رِضْوَانُ اللَّهِ عَلَيْهِمَا فَلَمَّا قُتِلَ عُمَرُ أَسْفَرَ بِهَا عُثْمَانُ رِضْوَانُ اللَّهِ عَلَيْهِ»  

[Machine] The translation of the passage is: "The Messenger of Allah ﷺ used to start with 'Bismillah ar-Rahman ar-Rahim' (In the name of Allah, the Most Gracious, the Most Merciful), as did Abu Bakr and Umar."  

أَنَّ رَسُولَ اللهِ ﷺ كَانَ يُسِرُّ بِبِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ وَأَبُو بَكْرٍ وَعُمَرُ ؓ  

"I prayed behind the Messenger of Allah ﷺ, Abu Bakr, Umar and Uthman, may Allah be pleased with them, and I did not hear any of them say out loud: In the Name of Allah, The Most Gracious, The Most Merciful." (Using translation from Nasāʾī 907)  

«صَلَّيْتُ خَلْفَ رَسُولِ اللهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ فَلَمْ أَسْمَعْ أَحَدًا مِنْهُمْ يَجْهَرُ بِبِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ»  

"صليتُ خلفَ النبىِّ ﷺ ، وأبِى بكرٍ، وعمرَ، وعثمانَ فلم يجهرْ ببِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ".