In the qiṣāṣ example, what does “joining two contrasting meanings in one expression” refer to?

Musāwāt and Ījāz al-Qaṣr: Proportionate Wording and the Rhetoric of Qiṣāṣ

• The apparently contrasting concepts of retribution and life conveying one wisdom
• Replacing each word with its antonym
• Combining two unrelated judgments
• A purely morphological difference between two forms of wāw