Explanation of the statement of Imam al-Nawawi (may Allah have mercy on him) regarding what he quoted: "… And Allah the Exalted said: ((Whoever obeys the Messenger has obeyed Allah)) …"

The Shaykh : In the name of Allah, the Most Gracious, the Most Merciful.
The author (may Allah have mercy on him) said, in the context of the verses in the chapter on the command to preserve the Sunnah and its etiquettes: Obedience is compliance with the command, whether that is in performing what is commanded or in leaving what is prohibited. If the terms "obedience" and "disobedience" are used, then obedience refers to performing what is commanded, and disobedience refers to performing what is prohibited. However, if "obedience" is used in an absolute sense, it includes both commands and prohibitions; that is, complying with commands is obedience, and avoiding prohibitions is obedience. Thus, the one who obeys the Prophet (peace and blessings be upon him) in his commands and prohibitions—meaning, if he commands him, he complies, and if he prohibits him, he avoids it—becomes obedient to Allah (Mighty and Majestic). This is the explicit meaning of the verse, and its implied meaning is that whoever disobeys the Messenger has disobeyed Allah. In this, there is evidence in this verse that what is established in the Sunnah is like what is established in the Qur'an; that is, it is part of the Shari'ah of Allah, and it is obligatory to adhere to it. It is not permissible for anyone to distinguish between the Book and the Sunnah in what is established from the Prophet (peace and blessings be upon him). The Prophet (peace and blessings be upon him) warned when he said: Meaning, he warns that a time may come upon people when they say, "We will not follow except what is in the Qur'an, but as for the Sunnah, we will not take it." This matter has occurred, and we have found among the atheists those who say, "We do not accept the Sunnah, we do not accept except the Qur'an." The truth is that they are liars, for they did not accept the Sunnah nor the Qur'an, because the Qur'an indicates the obligation of following the Sunnah, and that what came in the Sunnah is like what came in the Book of Allah. But they deceive the common people and say that since the Sunnah is not a Qur'an that is recited and transmitted by mass transmission among the Muslims, it is subject to doubt, subject to forgetting, subject to error, and the like. Then the author mentioned the saying of Allah the Exalted: This is a warning from Allah (Mighty and Majestic), a warning to those who deviate from the command of the Messenger (peace and blessings be upon him), meaning, they turn away from his command and contradict it. For this reason, it did not say "they contradict his command," but rather "they deviate from his command," meaning they turn away from it and contradict it. He warned them that a trial may befall them, or a painful punishment may befall them. Imam Ahmad said: "Do you know what the trial is? The trial is shirk (associating partners with Allah). Perhaps if he rejects some of his saying, something of deviation may enter his heart and he will perish" and refuge is sought in Allah. If he rejects something of the saying of the Messenger (peace and blessings be upon him), perhaps something of deviation may enter his heart and he will perish. This perishing is not physical perishing, but religious perishing, and religious perishing is more severe than physical perishing. Physical perishing is the end of every living being, whether his life is long or short, but religious perishing is the loss of this world and the Hereafter, and refuge is sought in Allah. And His saying: means that they are punished; they are punished before the trial befalls them. We ask Allah for well-being. In this is evidence of the obligation to accept the command of the Prophet (peace and blessings be upon him), and that the one who deviates from it is threatened with this punishment, that a trial may befall them or a painful punishment may befall them. And Allah grants success.
The reader: The author (may Allah have mercy on him) quoted, in the context of mentioning the verses in the chapter on the command to preserve the Sunnah, "And He said:

And indeed, [O Muhammad], you guide to a straight path - ⁽⁵³⁾ The path of Allah

وإنك لتهدي إلى صراط مستقيم * صراط الله

[Ash-Shuraa 42:52-53]

And He said:

So let those beware who dissent from the Prophet's order, lest fitnah strike them or a painful punishment.

فليحذر الذين يخالفون عن أمره أن تصيبهم فتنة أو يصيبهم عذاب أليم

[An-Nur 24:63]

And He said:

And remember what is recited in your houses of the verses of Allah and wisdom

واذكرن ما يتلى في بيوتكن من آيات الله والحكمة

[Al-Ahzab 33:34]

And the verses in the chapter are many".