Asim ibn Abi al-Najud, an eighth century reciter and teacher based in Kufa, one of early Islam's major centers of Quranic and legal scholarship, is remembered as one of the most careful and widely respected reciters of his generation, his reading eventually recognized as one of the seven canonical qira'at codified by later scholarship. Asim transmitted his reading to two principal students whose own versions came to be recognized as distinct riwayat within the broader Asim reading, Hafs ibn Sulayman and Shu'ba ibn Ayyash, and while both transmissions remain formally canonical and valid, it is specifically Hafs's version of Asim's reading, rather than Shu'ba's, that came to overwhelmingly dominate later practice.
Hafs, who was also Asim's stepson according to traditional biographical accounts, is credited with a particularly precise and well documented chain of transmission for the reading that bears his name, a reputation for reliability that likely contributed, alongside later historical and institutional factors, to his version's eventual position as the most widely used Quranic reading of all. Asim himself is described in traditional biographical sources as having studied under two separate teachers for the consonantal text and for its precise recitation, a dual line of instruction he is said to have deliberately kept distinct and later transmitted onward as a combined, internally consistent reading, a degree of documented methodological care that traditional scholarship treats as part of why his transmission was judged reliable enough to be preserved and eventually canonized alongside the other six recognized readings.