question #1 Sahih al-Bukhari 3796, Book 63, Hadith 21 : What significance does the pledge of allegiance hold in the context of Jihad according to Islamic teachings?

On the day of the battle of the Trench (i.e. Ghazwat-ul-Khandaq) the Ansar used to say, “We are those
who have given the pledge of allegiance to Muhammad for Jihad (i.e. holy fighting) as long as we
live.” The Prophet (ﷺ) , replied to them, “O Allah! There is no life except the life of the Hereafter; so
please honor the Ansar and the Emigrants.”