the matter of will He instructed that it be expressed with the particle thumma ("then"). That is because obedience to the Messenger is obedience to Allah: whoever obeys the Messenger has obeyed Allah, and obedience to Allah necessarily entails obedience to His Messenger. Will, by contrast, is another affair altogether: no servant’s will is Allah’s will, and Allah’s will is in no way dependent on the will of His creatures. Whatever Allah wills comes to pass even if people do not will it, and whatever people will cannot occur unless Allah wills it.
[The Meaning of the Testimony that Muhammad is the Messenger of Allah]
The second foundation concerns the right of the Messenger, peace and blessings be upon him. We are obliged to believe in him, obey him, follow him, seek his good pleasure, love him, submit to his judgment, and so forth. Allah, Exalted be He, says: “Whoever obeys the Messenger has indeed obeyed Allah” (Qur’an 4:80). He also says: “Allah and His Messenger are more deserving that they should please Him…” (Qur’an 9:62).