question #3 Sahih al-Bukhari 4173, Book 64, Hadith 215 : How were announcements made to the companions of the Prophet (ﷺ) regarding new instructions or prohibitions?

(who was one of those who had witnessed (the Pledge of allegiance beneath) the Tree) While I was
making fire beneath the cooking pots containing donkey’s meat, the announcer of Allah’s Messenger (ﷺ)
announced, “Allah’s Messenger (ﷺ) forbids you to eat donkey’s meat.”