The Hanafi school or Hanafism is the largest school of Islamic jurisprudence out of the four principal schools within Sunni Islam. It developed from the teachings of the jurist and theologian Abu Hanifa, who systemised the use of reasoning. Hanafi legal theory primarily derives law from the Quran, the sayings and practices of Muhammad, scholarly consensus and analogical reasoning, but also considers juristic discretion and local customs. It is distinctive in its greater usage of qiyas than other schools.