Why is يَا وَلَدُ the key contrast with يَا إِبْرَاهِيمُ?
- إِبْرَاهِيمُ is already a proper-name definite, while وَلَدٌ is originally indefinite and becomes definite for the intended addressee
- Both words are verbs
- Both are definite idafahs
- وَلَدُ contains ال