ANSWER:

This does not invalidate the tawaf as saying bismillah, Allahuakbar is not mandatory. However, after finishing the last round and passing the black stone, you don’t say this.

While performing Tawaf, we do 7 rounds in which we have to say ‘Bismillah Allahu Akbar’ by pointing hand every time we come in line with black stone, so that’s saying ‘Bismillah Allahu Akbar’ 8 times in total. Out of 8 times, if someone forgets to say ‘Bismillah Allahu Akbar’ once or twice, is his Tawaf invalid?