Sahih Muslim 399 c
The Book of Prayers
The Proof Of Those Who Say That The Basmalah Should Not Be Recited Aloud
'Abda reported: 'Umar b. al-Khattab used to recite loudly these words: Subhanak Allahumma wa bi hamdika wa tabarakasmuka wa ta'ala jadduka wa la ilaha ghairuka [Glory to You,0 Allah, and Your is the Praise, and Blessed is Your Name. and Exalted is Your Majesty. and there is no other object of worship beside You]. Qatada informed in writing that Anas b. Malik had narrated to him: I observed prayer behind the Messenger of Allah (ﷺ) and Abu Bakr and Umar and 'Uthman. They started (loud recitation) with: AI-hamdu lillahi Rabb al-'Alamin [All Praise is due to Allah, the Lord of the worlds] and did not recite Bismillah ir- Rahman-ir-Rahim (loudly) at the beginning of the recitation or at the end of it.