«إِمَّا أَنْ تَكُونَ فِي أَصْلِ السَّنَدِ ... أَوْ لَا يَكُونَ كَذَلِكَ بِأَنْ يَكُونَ التَّفَرُّدُ فِي أَثْنَائِهِ»
Singularity may occur at the original point of transmission; alternatively, it may occur within a later part of the chain.
First configuration: an early transmitter alone carries a report at the pivotal stage, even if numerous later students and paths develop.
Second configuration: several persons transmit from the Companion, but at a later stage one particular student's transmission is isolated along a specific route.
This distinction is based on the location of the isolated transmission, not the rarity of a report's wording, the report's public popularity, or a pre-established judgment of soundness or weakness.