question #3 Sahih al-Bukhari 7208, Book 93, Hadith 68 : What does the act of giving an oath of allegiance symbolize in the context of Islamic teachings?

We gave the oath of allegiance to the Prophet (ﷺ) under the tree. He said to me, “O Salama! Will you not
give the oath of allegiance?” I replied, “O Allah’s Messenger (ﷺ)! I have already given the oath of allegiance
for the first time.” He said, (Give it again) for the second time.