The point, then, is that when a hadith is transmitted, for example, through two different lines of transmission with no prior collusion between the narrators, it is just as impossible for it to be an error as it is for it to be a fabrication. Error does not usually encompass an entire lengthy, multifaceted incident; it touches only parts of it. So if one narrator relates a long, detailed story and another conveys it exactly as the first did—with no coordination between them—error in all of it is ruled out, just as deliberate invention in all of it is ruled out in the absence of collusion. Hence, any inaccuracy that may arise in such circumstances concerns only a detail of what took place in the narrative—like the report of the Prophet’s purchase of a camel from Jabir. Anyone who studies its chains of transmission will know with certainty that the hadith is authentic (1), even though the narrators disagreed over the exact amount of the price.
Commentary
This is precisely what we noted a moment ago: if the narrative contains fine or delicate points, one route of transmission is not sufficient; a second corroborating chain is required to establish it.