—for it may be that the Prophet’s ﷺ ruling that “The child is to be attributed to the marital bed” never reached them, so they held that the child belongs to the one who impregnated his mother and believed that Abū Sufyān was the one who had impregnated Sumayyah, Ziyād’s mother.
Indeed, this ruling can be unknown to many people, especially before the Sunnah became widely disseminated, for the pre-Islamic custom had been exactly that; or some other impediment may bar this cause of the threat from producing its effect—such as good deeds that erase misdeeds, and the like.
This is a broad field, for it includes every matter prohibited by the Book or the Sunnah when part of the ummah has not received the proofs of its prohibition and therefore deem it permissible, or when other proofs, in their view, outweigh those proofs, and they strive to weigh the evidence according to their own understanding and knowledge.
A prohibition carries certain legal consequences—sin, blame, punishment, moral deviance, and the like—but those consequences have conditions and impediments. Thus the prohibition may be firmly established while its consequences are lifted because the conditions are absent or an impediment is present; or the prohibition itself may be lifted for a given person while remaining in force for others.
We have revisited this discussion because people hold two opinions on the issue. The first—adopted by the majority of the early generations and the jurists—is that Allah’s ruling is one, and that whoever departs from it on the basis of a permissible ijtihād is mistaken yet excused and rewarded.