question #1 Sahih al-Bukhari 630, Book 10, Hadith 27 : What is the significance of pronouncing Adhan and Iqama before starting a prayer during a journey?

Two men came to the Prophet (ﷺ) with the intention of a journey. The Prophet (ﷺ) said, “When (both of) you
set out, pronounce Adhan and then Iqama and the oldest of you should lead the prayer.”