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}
"The Messenger of Allah ﷺ led us in prayer, and we did not hear him recite: In the Name of Allah, the Most Gracious, the Most Merciful. And Abu Bakr and Umar led us in prayer and we did not hear it from them either."
صَلَّى بِنَا رَسُولُ اللَّهِ ﷺ فَلَمْ يُسْمِعْنَا قِرَاءَةَ { بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ } وَصَلَّى بِنَا أَبُو بَكْرٍ وَعُمَرُ فَلَمْ نَسْمَعْهَا مِنْهُمَا
"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 }
"If Abdullah bin Mughaffal heard any one of us recite: 'In the Name of Allah, the Most Gracious, the Most Merciful', he would say: 'I prayed behind the Messenger of Allah ﷺ and behind Abu Bakr and behind Umar-may Allah be pleased with them both- and I did not hear any of them recite: 'In the Name of Allah, the Most Gracious, the Most Merciful."
سَمِعَ أَحَدَنَا يَقْرَأُ { بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ } يَقُولُ صَلَّيْتُ خَلْفَ رَسُولِ اللَّهِ ﷺ وَخَلْفَ أَبِي بَكْرٍ وَخَلْفَ عُمَرَ ؓ فَمَا سَمِعْتُ أَحَدًا مِنْهُمْ قَرَأَ بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ
Yahya related to me from Malik from Humayd at-Tawil that Anas ibn Malik said, "I stood behind Abu Bakr and Umar and Uthman and none of them used to recite 'In the name of Allah, the Merciful, the Compassionate' when they began the prayer."
قُمْتُ وَرَاءَ أَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ فَكُلُّهُمْ كَانَ لاَ يَقْرَأُ {بِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ} إِذَا افْتَتَحَ الصَّلاَةَ
[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] 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
"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 اللَّهِ ﷺ وَأَبِي بَكْرٍ وَعُمَرَ وَعُثْمَانَ رِضْوَانُ اللَّهِ عَلَيْهِمْ فَلَمْ أَسْمَعْ أَحَدًا يَجْهَرْ بِبِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ»
"The Messenger of Allah ﷺ led us in prayer, and we did not hear him recite: In the Name of Allah, the Most Gracious, the Most Merciful. And Abu Bakr and Umar led us in prayer and we did not hear it from them either." (Using translation from Nasāʾī 906)
«صَلَّى بِنَا رَسُولُ اللهِ ﷺ فَلَمْ يُسْمِعْنَا قِرَاءَةَ بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ وَصَلَّى بِنَا أَبُو بَكْرٍ وَعُمَرُ فَلَمْ نَسْمَعْهَا مِنْهُمَا»
"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»
"If Abdullah bin Mughaffal heard any one of us recite: 'In the Name of Allah, the Most Gracious, the Most Merciful', he would say: 'I prayed behind the Messenger of Allah ﷺ and behind Abu Bakr and behind Umar-may Allah be pleased with them both- and I did not hear any of them recite: 'In the Name of Allah, the Most Gracious, the Most Merciful." (Using translation from Nasāʾī 908)
سَمِعَ أَحَدًا يَقْرَأُ بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ يَقُولُ «صَلَّيْتُ خَلْفَ رَسُولِ اللهِ ﷺ وَخَلْفَ أَبِي بَكْرٍ وَخَلْفَ عُمَرَ فَمَا سَمِعْتُ أَحَدًا مِنْهُمْ قَرَأَ بِسْمِ اللهِ الرَّحْمَنِ الرَّحِيمِ»
"صليتُ خلفَ النبىِّ ﷺ ، وأبِى بكرٍ، وعمرَ، وعثمانَ فلم يجهرْ ببِسْمِ اللَّهِ الرَّحْمَنِ الرَّحِيمِ".