«وَإِمَّا أَنْ تَكُونَ مُنَافِيَةً ... فَيُقْبَلُ الرَّاجِحُ وَيُرَدُّ الْمَرْجُوحُ»
If the addition is incompatible with its counterpart, the stronger version is preferred and the weaker is rejected.
The two accounts cannot both be accepted in the same sense. It is not enough that the person reporting the addition is trustworthy: compare their precision, the collective routes, and the signs identifying the more accurately preserved report.
Illustration: One text explicitly affirms particular wording while another explicitly denies that wording in the very same occurrence, and no reasonable distinction between occasions remains. This calls for actual comparison, not automatic acceptance.