Kutub as-Sittah

Abu Abdullah Muhammad ibn Yazid ibn Majah (829–887 CE) compiled Sunan Ibn Majah, the sixth and most debated of the six canonical Sunni hadith collections. It is noted for its broad coverage and many unique traditions, though it includes more weak and disputed reports than the others.

Abu Dawood Sulaiman ibn al-Ash'ath (817–889 CE) was one of the six canonical hadith scholars of Sunni Islam. His Sunan Abu Dawood, distilled to about 4,800 hadith, was the first major collection organized around Islamic legal topics, becoming an essential reference for jurists.

Ahmad ibn Shu'ayb al-Nasa'i (829–915 CE) was one of the six canonical hadith scholars of Sunni Islam. His al-Sunan al-Sughra (al-Mujtaba) is distinguished by exceptionally rigorous narrator criticism — standards so demanding he rejected narrators other major scholars accepted.

Abu Isa Muhammad ibn Isa al-Tirmidhi (824–892 CE) compiled Jami' al-Tirmidhi, the fourth of the six canonical Sunni hadith collections. He systematized the 'hasan' (good) grade of authenticity, and his legal commentary alongside each hadith made the work valuable for jurisprudence.