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.
Reference: Sahih Muslim 399 a In-book : Book 4, Hadith 52 USC-MSA web (English) : Book 4, Hadith 786 (deprecated)
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