Isnād iḍṭirāb may arise when a report is variously attributed through one transmitter, through his father, or through substantially different routes with no sound basis for choosing among them. Chain-level iḍṭirāb is relatively frequent.
Matn iḍṭirāb arises where incompatible textual variants cannot be reconciled or decisively preferred. Not every verbal variation counts: synonymous expression and compatible diversity are different matters.
Critical questions: 1. Do the variants actually conflict? 2. Is one transmitter more accurate? 3. Are independent corroborating routes present? 4. Does the variation materially affect the report?
Only after these inquiries can one judge irreconcilable and equally supported variation. If a preponderant form is established, the report is not simply left classified as muḍṭarib.