Three pieces of source evidence

ʿAṭf al-Bayān: Definition, Examples, and Contrast with Badal

تَابِعٌ غَيْرُ صِفَةٍ يُوَضِّحُ مَتْبُوعَهُ — the definition.

قَامَ أَبُو حَفْصٍ عُمَرُ — straightforward identity clarification.

أَنَا ابْنُ التَّارِكِ الْبَكْرِيِّ بِشْرٍ — the technical example showing a difficulty for badal.

These are the three pillars of the book’s short chapter.