But, when they started following the scholars of other...

But, when they started following the scholars of other sects, they started writing books on Principles and Jurisprudence; they introduced Consensus and Evidence of reason also as sources of law.

When it was pointed out to them that this was against the teachings of the AHl Ul Bayt (a.s.), they tried to explain it away by saying that the consensus includes the person of the Infallible Imam (a.s.), whilst the evidence of reason on its own is not a source but is part of the evidence which forms the law. This then led to the introduction of analogy (Qiyas) in the Shiite sect. This was the time when referring to the Holy Quran and the traditions as sources of law, came to an end.