«رَبِّ اشْرَحْ لِي صَدْرِي»
My Lord, expand my breast for me.
This is Qurʾān 20:25. The opening request “expand for me” invites the question of what is to be expanded; ṣadrī (صدري) then specifies the object and sharpens the prayer's effect.
In clarification after initial generality (الإيضاح بعد الإبهام), the first part creates a genuine expectation and the later part resolves it. Not every long sentence qualifies; the initial expression must actually leave room for meaningful specification.