Yahya ibn Muin

Yahya ibn Muin al-Baghdadi (158–233 AH / 775–848 CE) was one of the three founding figures of the classical science of hadith criticism (jarh wa ta'dil), alongside Ali ibn al-Madini and Ahmad ibn Hanbal. He was born in Anbar near Baghdad and devoted his entire life to the single task of evaluating the reliability of hadith narrators. He is considered one of the most authoritative voices in the history of Islamic hadith science.

He traveled extensively across the Muslim world — to Yemen, Egypt, Syria, Hijaz, and Khorasan — to learn hadith and to scrutinize narrators. He reportedly spent on his scholarly travels an inheritance of one million dirhams, a fortune that he expended entirely on the pursuit of hadith. Despite this extraordinary expenditure, he died owning almost nothing of material value.

His evaluations of narrators — recorded in numerous works and transmitted by his students including Abbas al-Duri — became the standard reference for the classical hadith collections. Al-Bukhari, Muslim, Abu Dawud, al-Tirmidhi, and virtually every major hadith scholar relied on his judgments. He would give brief, often one-word or one-line verdicts on each narrator: "thiqah" (reliable), "layyis" (weak), "laysa bi-shay'" (nothing worth mentioning), or more severe condemnations.

He died in Medina during pilgrimage in 233 AH. His scientific approach to narrator evaluation, based on personal knowledge and direct experience with transmitters rather than hearsay, set the standard for hadith criticism that has been followed by Islamic scholarship for over a millennium.