Usul al fiqh of Zaydi school

wa alaykum as salaam wa rahmatullahi wa barakatuhu.

Thank you for your question! According to one of our great imams and usuli, Imam Mansur Billah al-Qaasim bin Muhammad, upon him be peace, the usul are four. He said in his Kitaab al-I'tisaam [1:169]:

Know that the proofs that are obligatory to act upon are: the Book of Allah, the Sunnah of Allah's Messenger, consensus and analogical reasoning (qiyaas).

By consensus, he means the consensus of Ahl al-Bayt (as).

As for analogical reasoning, Imam Mansur Billah, upon him be peace, said that it refers to those matters in which the explicit text of the Qur'an or Sunnah are silent about. One is to use analogical reasoning from the Qur'an and Sunnah to judge those matters. He also said that consensus takes precedence over analogical reasoning and that analogical reasoning utilising the Book and Sunnah takes precedence over opinion.

And Allah knows best!

IRS

Oops! Sorry for the confusion! I mean consensus of the imams descended from Ahl al-Bayt.

And Allah knows best!

IRS

Thank you for your question!

There are many books dedicated to Zaydi usul al-fiqh. The most famous is Al-Kaafil . There have been numerous commentaries written on it. Some of our imams authored books on usuul. Imam Mansur Billah al-Qaasim bin Muhammad (as) authored a small booklet and Imam Ahmed bin Yahya (as) also authored a text on usuul.

Hope this helps! And Allah knows best!

IRS