Deliberate fabrication is knowingly inventing or spreading words as the Prophet’s ﷺ when they are not his. An unintentional error, such as a memory lapse, is different, although correction may still be necessary.
If uncertain of a report’s wording or attribution, consult the original reference, ask someone qualified, or refrain from making a definite claim. Beginners should not pronounce arbitrary judgments on every circulating quotation.
The strong wording فَلْيَتَبَوَّأْ مَقْعَدَهُ مِنَ النَّارِ communicates the seriousness of this trust; it is not an invitation to determine a particular individual’s ultimate fate.