What are the sources of sound doctrine after the Qur’an and Sunnah, and where can one obtain a complete interpretation of the Holy Qur’an?

The source of the correct creed—the creed of Ahlus-Sunnah wal-Jama’ah—is the Qur’an, the Sunnah, and what has been agreed upon by the imams of the religion from among the Companions and the Tabi’in. This is known as the methodology of the Pious Predecessors (Salaf Sālih).

Ahlus-Sunnah wal-Jama’ah follow the traditions of the Messenger of Allah, peace be upon him, and the Sunnah of the Rightly Guided Caliphs. They know that the most truthful speech is the speech of Allah, and the best guidance is the guidance of Muhammad, peace be upon him.

Consensus (Ijma’) is considered the third principle upon which Ahlus-Sunnah rely in knowledge and religion. With these three principles, they weigh all statements and actions related to religion. The valid consensus is the consensus of the Pious Predecessors.

As for the interpretations of the Qur’an, there is no single book that encompasses all the sciences of the Qur’an. Rather, the student of knowledge chooses what suits his needs and academic level.