There are 6 collections of Hadiths that are considered Sahih ("reliable"). I am asking who it was that decided these collections should be Sahih. Furthermore, how did they come to this conclusion? For example, to determine the books that would make up the "official" Bible, the Council of Nicea was convened. So, was it a group of scholars, and if so who were they; or, if it was a single scholar, who was that? If there was some other means of determining, what was it? Thank you much.