Mentioning the statement of al-Shafi'i (may Allah have mercy on him): "The entire Sunnah is what Allah (Blessed and Exalted is He) made understood to His Prophet (peace and blessings be upon him)"

The Shaykh : And for this reason, it is reported from Imam al-Shafi'i (may Allah have mercy on him) that he said: "The entire Sunnah" — meaning, naturally, what is authentic of it — "is what Allah (Blessed and Exalted is He) made understood to His Prophet (peace and blessings be upon him)."
Imam al-Shafi'i means that the Qur'an encompasses the Sunnah, and that Allah (Mighty and Majestic) inspired His Prophet (peace and blessings be upon him) to explain what the Muslims needed explained from the noble verses. This is one example, and that is sufficient for you.
So the rule in interpreting the Qur'an — I return to remind you — is that it is only by referring to the Qur'an and the Sunnah. One should not say "referring to the Qur'an, then the Sunnah," because that explicitly places it in the second position. We do not wish to speak in a manner befitting only scholars, so we say: Yes, in terms of its transmission, the Sunnah is in the second position relative to the Qur'an, which came to us as mass-transmitted. But in terms of practice, the Sunnah is like the Qur'an; it is not permissible to differentiate between Allah and His Messenger (peace and blessings be upon him), between the speech of Allah and the speech of His Messenger (peace and blessings be upon him). The differentiation observed by some specialized scholars in the science of hadith is a differentiation that pertains to the science of transmission (riwayah). As for what pertains to the science of understanding (dirayah), jurisprudence, and comprehension of the Book, there is no difference between the Book of Allah and the hadith of the Messenger of Allah (peace and blessings be upon him).