Due to some issues which arose in the second century of Hijrah, the muhaddiseen took the matter of authentication of the hadith seriously. The main issue was the fabrication of the hadith as many hypocrites wanted to do so. It was not an easy task. Imam Abdullah bin Ismail Bukhari, imam Muslim, and other scholars took this matter seriously and introduced some principles to be followed while authenticating the hadith. There are two parts in which a hadith is divided. The first part is considered as Sanad while the other part is called Matan. We can have example of Imam Bukhari hadith as “It is reported to us by Ubaidullah saying he heard Hanzalah who came to know from Ikramah saying he heard Ibn-e-Umar who narrates from the Prophet (PBUH):

The first of this hadith which informs about the transmitters is called Isnad while the second part which contains the text is called Matan.

    

The Muhaddiseen always assessed both parts of the hadith thoroughly. There was an art which was called Asma-ur-Rijal. This art was used to judge the credibility of any narrator. The muhaddaseen assessed the chain of the narrators carefully and observed strictly through this art. They collected the biographies of the narrators as well to investigate in detail. There were very strict conditions like the transmitter should have firm possession in faith and excellent memory with good character. If any transmitter cheated or lied to anyone especially on the matter of hadith. If any record of cheating or lying was found, the narrator’s hadith was rejected. There was another strict condition followed in the transmission of hadith that the first transmitter had to be from the companions of the Holy Prophet Muhammad (Peace be upon him) and the chain of the transmitters should not be interrupted at any stage. This was the way to collect the first part of the hadith which is called Isnad. 

In the same way, the Matan (also known as text) was also checked thoroughly with some principles. It was ensured that the hadith is according to the teachings of the Quran and Sunnah and not in contradiction with any of those two.  The example can be given as no hadith will be considered as authentic if it is regarding six prayers in a day. It should also be acceptable logically. An example can be taken as no one can live for a month without eating and drinking so if any text is for fasting a whole month without eating or drinking comes from any source, it will be rejected. The text or Matan can’t condemn or praise any person or tribe from history or for future events by name. The six books which are considered authentic after the Holy Quran are called Sihah-e-Sitta.