question #3 Sahih al-Bukhari 800, Book 10, Hadith 195 : Why might observers think that the Prophet (ﷺ) had forgotten the prostration during his prayer?

Anas used to demonstrate to us the prayer of the Prophet (ﷺ) and while demonstrating, he used to raise his
head from bowing and stand so long that we would say that he had forgotten (the prostration).