The World Federation One Stop Fiqh

Ruling 994

If a person recites Sūrat al-Ḥamd in the third and fourth rakʿahs, it is not obligatory for him to also recite its bismillāh in a whisper except if he is a follower in congregational prayers, in which case the obligatory precaution is that he must also recite bismillāh in a whisper.