فَأَرَدْتَ -أَرْشَدَكَ اللَّهُ- أَنْ تُوَقَّفَ عَلَى جُمْلَتِهَا مُؤَلَّفَةً مُحْصَاةً، وَسَأَلْتَنِي أَنْ أُلَخِّصَهَا لَكَ فِي التَّأْلِيفِ بِلَا تَكْرَارٍ يَكْثُرُ،
You sought to have the reports assembled and enumerated, and asked me to compile an abridged work without abundant repetition.
“Muʾallafah” indicates organized compilation; “muḥṣāh” indicates an accounted-for corpus. The immediate aim of abridgement is to avoid needless repetition without sacrificing necessary evidence or intended meaning.
Imam Muslim later allows a relevant part of a report to be quoted separately where this can be done without losing its necessary context and meaning. Repetition that preserves a significant additional meaning or serves scrutiny of a chain is useful; selective quotation that distorts the report is not legitimate abridgement.