What does «khaṣaṣtu fulānan bi-l-dhikr» help explain?

The Separating Pronoun (Ḍamīr al-Faṣl): Restriction, Emphasis and Predication

• Singling someone out for a particular treatment
• An imperative requirement for ḍamīr al-faṣl
• A prohibition on postponing the predicate
• The delay indicated by thumma