Is it permissible to pledge allegiance to the Messenger of Allah, may Allah bless him and grant him peace, in this time, and how would this pledge be made, and what are its obligations?

A Muslim must obey and follow the Prophet, peace and blessings be upon him, because Allah Almighty says: "Say, 'Obey Allah and obey the Messenger,'" and because the Prophet, peace and blessings be upon him, said: "Whoever obeys me has obeyed Allah, and whoever disobeys me has disobeyed Allah." As for claiming to pledge allegiance to the Messenger, peace and blessings be upon him, in this time, it is a lie, because he is dead.