Ash Shaykh Muhammad Hizaam mentioned clarifying the importance of Usool al Fiqh for the student of knowledge:
“Knowledge of Usool Al Fiqh (principles of jurisprudence) is a beneficial knowledge, every student of knowledge is in need of it for Fiqh. If a Faqeeh (scholar of jurisprudence) does not have this knowledge, he will fall into many errors. He may use as evidence a general narration while there is that which specifies it. He might use as evidence an unrestricted narration while there is that which restricts it. Similarly, he might use as evidence an abrogated text. Perhaps there may be some evidences that may seem to contradict one another and he is not able to reconcile between them.
This knowledge which the scholars have placed, the principles of jurisprudence, then it is principles that gradually leads a student until they understand how to derive rulings and understand how to reach a legislative ruling in a specific affair […] The first one to write in this knowledge was Imam As Shaafiee in his famous book called ‘Ar Risaalah’ which he wrote when Imam Abdurrahman Ibn Mahdi who was a young man at the time asked Imam Ash Shaafiee to write a book for him clarifying to him affairs like abrogation, deriving evidences from the book and Sunnah and other affairs. Ash Shaafiee wrote this book for him, and Abdurrahman Ibn Mahdi would often make Dua for him due to it. It is also reported that Abdurrahman Ibn Mahdi said he read the book ‘Ar Risaalah’ 500 times and each time he would benefit something new.” End. [Al Fawaaid wat Tawdeehaat page 11-12]
Majid Jawed Al-Afghanee