What is the meaning of Mu'awiyah's acceptance of Umm Salamah's testimony alone in establishing the right of two men against another, and can such a right be established by the testimony of one woman without an oath, and what is the scholars' opinion on this?

The mentioned report's origin is not confined to Abd al-Razzaq alone, nor has anyone been found who authenticated it. Even if it were authentic, Mu'awiyah (may Allah be pleased with him) might have found evidence confirming its veracity. In any case, rights are not established by the testimony of a single person, except for what Allah specifically granted to Khuzaymah (may Allah be pleased with him), as the Prophet (peace and blessings of Allah be upon him) made his testimony equivalent to that of two men.