Is it true what some misguided sects claim regarding the accusation of adultery against the mothers of some Companions and their Successors?

He who witnesses adultery, but the four witnesses required are not met, is forbidden from speaking about what he saw. If he testifies to it, then his حكم (ruling) is that he is a liar. Accusing someone of adultery necessitates impugning lineage, which is a practice from the days of Jahiliyyah (pre-Islamic ignorance). Lying knows no bounds, and those who make claims unsupported by evidence are impostors.