Here is what Sayyid Ibn Taoos (r.a.) says to his son about how Muslims have treated Prophet (s.a.wa.) while in a haste to usurp caliphate:
May Allah keep His Mercy and Grace away from the people who abandoned the corpse of the Prophet (s.a.w.a.) and were engrossed in choosing the caliph, whose basis was in prophethood and messengership of prophet (s.a.w.a.). They did this only to deprive his Ahle Bait of leadership.
O my son! By Allah! I do not understand what humanity, intellect, manliness, conscience and companionship these people had after the numerous obligations and compassion showered upon them by the Prophet (s.a.w.a.)!
How rightly Imam Zainul Abideen (a.s.) had said:
By Allah! Had it been possible for the nation to seek kingship without associating with prophethood of the Prophet (s.a.w.a.), they would most certainly have turned away from his prophethood.
- Kashf al-Muhajjah p 125-126