What two functions coincide in the poetic use of “fa-ṣabrun jamīl”?

Iqtibās and Taḍmīn: Quoting Scripture and Incorporating Poetry

• Taking and passing off another poet’s complete verse
• Completely reversing all letters of the hemistich
• Completing the conditional response and recalling familiar Qur’anic wording
• A grammar exercise without a rhetorical relation