How do we respond to someone who questions the Qur’an’s completeness, arguing that some religious rulings are based solely on the Sunnah, such as the exception of fish and locusts from the general prohibition of carrion in His — Exalted be He — saying: "Forbidden to you are carrion and blood"?

The Sunnah of the Prophet is a revelation from Allah, and an explanation and clarification of the Holy Quran. It particularizes the general, restricts the absolute, and clarifies the ambiguous. The verse: "Forbidden to you are carrion and blood" is an example of this. The Sunnah has specified from these, fish, locusts, liver, and spleen, based on the Prophet’s (peace be upon him) saying: "Two dead things and two types of blood have been made lawful for us. As for the two dead things, they are fish and locusts. As for the two types of blood, they are liver and spleen." Both are from Allah, and it is obligatory to follow what the Messenger of Allah (peace be upon him) commanded. For legal rulings are either detailed in the Quran, or general and detailed by the Sunnah, or the Sunnah independently states their ruling.