Where do the differences among madhhabs originate from?

The differences originate from different reasons. People may understand the verses that express judgments or decrees (nass) in the Quran differently because nass have different parts as it is stated in the method of fiqh: khafi (secret), mujmal (ambiguous), sarih (clear), kinaya (implied), majaz (metaphorical), haqiqah (real), mutlaq (absolute), muqayyad (restricted), khas (specific), amm (general). Therefore, mujtahids can understand the nass differently.

Furthermore, hadiths have some types, too: mutawatir (reported by a large number of people that cannot be expected to agree upon a lie), mashhur (reported by a large number of people but not reaching the level of mutawatir), khabar wahid (reported by a single person), mursal (not going beyond tabi’in), muttasil (uninterrupted), munqati’ (broken), etc.

Mujtahids had different views about using those hadiths as evidence. Consequently, different opinions emerged.

The difference of opinion regarding the evidence and understanding the evidence that is accepted differently caused different judgments and decrees to appear regarding the same issue.

The customs and traditions of the places in which fatwas were issued affected the ijtihads of mujtahids, too.