question #1 Sahih Muslim 399a, Book 4, Hadith 52 : What is the practice of reciting Bismillah-ir-Rahman-ir-Rahim during prayer according to the companions of the Prophet?

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.