B336 From the Signposts of Tawheed

In this regard, many verses indicate the obligation of obeying the Prophet and adhering to his Sunnah. Also, previous evidence indicated the obligation of adhering to the Book of Allāh, sticking to it, and complying with his orders and abstaining from its prohibitions. These are two relevant fundamentals in which whoever denies one of them denies the other. This is considered an act of disbelief and misguidance which takes one outside the fold of Islām as agreed by all the scholars.

The ahādīth of the Prophet (May Allah raise his rank and grant him peace) indicated the obligation of obeying the Messenger of Allāh (May Allah raise his rank and grant him peace), following his Sunnah and refraining from disobeying him. All of this is relative to the people of his era as well as those to come. It is related by Al-Bukhārī and Muslim on the authority of Abū Hurayrah (May Allah be pleased with him) that the Prophet (May Allah raise his rank and grant him peace) said:

“Whosoever obeys me, obeys Allāh; and he who disobeys me disobeys Allāh.”