ولو ترجح بعض وجوه المشترك ببيان من قبل المتكلم كان مفسرًا، وحكمه: أنه يجب العمل به يقينًا
When the speaker's own clarification selects one sense of a homonym, the expression is mufassar, and its stated sense is to be followed with certainty.
The distinction from muʾawwal is decisive: muʾawwal rests on a preponderant inference, while mufassar rests on clarification supplied by the speaker.
The certainty described here concerns the determination of the speaker's intended meaning, not automatic certainty about unrelated external facts.