question #1 Sahih al-Bukhari 94, Book 3, Hadith 36 : What is the significance of repeating a statement three times in communication?

Whenever the Prophet (ﷺ) asked permission to enter, he knocked the door thrice with greeting and
whenever he spoke a sentence (said a thing) he used to repeat it thrice. (See Hadith No. 261, Vol. 8).