We cannot find in any other sect the genuineness which characterizes the creed of the Ahl al-Bayt (A.S.) in the area of legislation, for it relies on a deep understanding of the Holy Qur'an and the pristine Prophetic Sunnah which derives from its original leading fountainhead a source of its legislation and such rules.
For example, according to a narrative, a man asked Imam al-Reza (A.S.) about another man who said at the time of his death, "Any old slave I have is now emancipated for the sake of pleasing God." The Imam said, "Yes, there is a way to determine who is `old' according to the Almighty and Praised God Who says in His Book, `... till it became like an old date cluster;' therefore, anyone among his slaves who has been with him for at least six months must now be freed."
The date cluster becomes old and dry during the period of six months. In this example, the Imam (A.S.) did not contend himself by just providing a legislative rule; he also derives its rule from the text of the Holy Qur'an.
Independence of the Ahl al-Bayt (A.S.) From Qiyas and Others
The Ahl al-Bayt (A.S.) did not sense the need to seek avenues which were distant from the legislative realities in the conclusions they reached such as qiyas (comparison), istihsan (preference), etc., which were regarded by others as indicative of the legislative rule when they lack a concrete text, due to the fact that, because of the knowledge and the secrets of the Message which they inherited from their grandfather the Messenger of God (S.A.W.) as well as their own level of iman (firm belief), they were self sufficient, independent, and due to what God had endowed them with of the faculty of knowledge in order they might be His Proofs over people.
The Ahl al-Bayt (A.S.) strongly condemned the use of qiyas and other such methods invented by others as means whereby they would justify their derivations when they lacked a concrete evidence. Because of this, many strong confrontations happened between them and these people, and we may discuss this subject in detail in our forthcoming book about Imam al-Sadiq (A.S.) because the most violent of such confrontations took place during his time when promoters of various sects were free to express their views.