I asked Anas whether the Prophet ﷺ used to begin his recitation with "In the name of Allah, the Most Gracious, the Most Merciful" [Fatihah 1:1] or with "All praise is due to Allah, Lord of all the worlds" [Fatihah 1:2].He replied, "You are asking me about something I do not remember, and no one has ever asked me about it before."
حدثنا غسان بن مضر
سألت أنسا أكان النبي ﷺ يقرأ {بسم الله الرحمن الرحيم} أو {الحمد لله رب العالمين} فقال إنك لتسألني عن شيء ما أحفظه أو ما سألني أحد قبلك
The chain of transmission is sahih. Likewise, Haythami graded it sahih in volume 2, page 108. This is the basis relied upon by Abu Hanifa and those who agree with him in not saying the basmalah aloud, because Anas denied the narration which states that it was said aloud.