Beside other things invented by those having controversy on...
Beside other things invented by those having controversy on kalam and fiqh (jurisprudence), for defending their views in these two sciences, and some other things foisted with the intention of propaganda for some political parties, in the primeval ages. Further, there were individuals indulged extensively in fabricating many traditions to make people in general and the upper class in particular, believe them to be of abundant knowledge and accurate awareness of the Prophet’s sayings and deeds.
All that had its considerable effect in corrupting the minds and causing views of many people to deviate from the straightforwardness in comprehending the religion and conceiving the Prophet as he should be conceived by all Muslims, free from all that absurdity which was falsely ascribed to him while he being totally exempted from it all.
Besides, this conduct was a means for opponents and enemies of Islam to find fault with and assault, unjustly and slandrously, the Din and the Messenger who brought it. The former muhaddithun have taken notice of all that, exerting their utmost to pick out the veracious traditions, cleansing them from the lies of the falsifiers and affectation of the pretenders.
The method they followed in this exertion was investigating the biography of the rijal who reported the hadith throughout epochs, till it was written down. They used to follow up every and each one of these rijal, verifying his being of pure conduct, sincere faith in Allah and His Messenger, earnest in telling the truth all the time and in his speech about the Prophet in particular.
It is really a commendable and fruitful effort that was exerted by those who are well-versed among the ‘ulama’ of hadith, making their best of the job in the extreme. This effort, despite its strenuousness and productivity, could never be enough, since the most difficult and complicated job is to study life of people, trying to recognize its details and minute matters.
May be you search and investigate without managing to discover any reality about people or their minute mysteries, or what is concealed in their minds, or any sort of weakness in their souls and conduct they insist on hiding. Another effort to be added to this one being to study the text itself.
The man might be sincere and trusted on the outside, in a way that when giving testimony it be accepted by all judges, but Allah alone is aware of all secrets and whatever is concealed in minds and kept inside hearts.