scholars" seeking to correct this problem. Some scholars (Daniel W. Brown, A. Kevin Reinhart) shed doubt on this. Brown believes the theory "fails" to adequately account "for the atmosphere of conflict" of at least early hadith criticism. The "method of choice" of partisans seeking to discredit opposing schools of Islamic law was to discredit the authorities (transmitters) of their opponent's hadith—to "tear apart" their isnads". (To do this required developing biographical evaluations of hadith transmitters—ʿilm al-rijāl and ilm jarh wa ta’dil). Reinhart finds descriptions of famous companions of Muhammad in Ibn Sa'd's Kitāb aṭ-ṭabaqāt al-kabīr "recording hadith and transmitting it, asking each other about precedents, and reproaching those who disregarded this authentic religious knowledge" in suspicious conformity to the "mythology of the pristine early community". As the criteria for judging authenticity grew into the six major collections of ṣaḥīḥ (sound) hadith (Kutub al-Sittah) in the third century, the science of hadith was described as having become a "mature system", or to have entered its "final stage". The classification of Hadith into sahih, sound or authentic; hasan, good; da'if, weak, (another rating is mawḍūʿ, fabricated). was utilized early in hadith scholarship by Ali ibn al-Madini (161–234 AH). Later, al-Madini's student Muhammad al-Bukhari (810–870) authored a collection, now known as Sahih Bukhari, commonly accepted by Sunni scholars to be the most authentic collection of hadith, followed by that of his student Muslim ibn al-Hajjaj. Al-Bukhari's methods of testing hadiths and isnads are seen as exemplary of the developing methodology of hadith scholarship. Evaluating authenticity An elaborate system was developed by scholars of hadith to determine the authenticity of traditions based on "two premises": that the authenticity of a hadith report is "best measured by the reliability of the transmitters" (known as rāwī pl. ruwāt) of the report; consequently, "carefully scrutinizing" the "individual transmitters" of the hadith (ilm jarh wa ta’dil; ʿilm al-rijāl) and "the continuity of their chains of transmission" is the best way to measure hadith reliability. A basic element of hadith studies consist of a careful examination of the chain of transmission (sanad , also isnād , or silsila ), relaying each hadith from the Prophet to the person who compiles the hadith. The isnād and the commentary are distinct from the matn (), which is the main body, or text, of the hadith, These two terms are the primary components of every hadith. According to the person most responsible