«وَأَمَّا مِنْ حَيْثُ اسْتِعْمَالُهُمُ الْفِعْلَ الْمُشْتَقَّ فَلَا يُفَرِّقُونَ»
In their use of related verbal forms, critics do not maintain the same distinction.
A critic may say “tafar rada bihi fulan” or “aghraba bihi fulan” in discussions of either absolute or relative singularity. A verb on its own therefore does not settle the classification.
Statement A: “A alone transmitted this report from his teacher” may be describing relative singularity.
Statement B: “Only A's route exists at the report's pivotal origin” directly points toward absolute singularity.
Working rule: consider the specific narrators and alternatives mentioned before and after the verb rather than inferring the category from the word tafarrada alone.