وَيَوْمًا عَلَى ظَهْرِ الْكَثِيبِ تَعَذَّرَتْ
عَلَيَّ وَآلَتْ حَلْفَةً لَمْ تَحَلَّلِ
And on another day, upon the crest of a sand dune, she held herself aloof from me and swore a firm oath without qualifying or releasing herself from it.
Al-kathīb is a dune formed by heaped sand; ʿalā ẓahri al-kathīb sets the scene on its upper ridge. Taʿadhdharat ʿalayya here means that she resisted, made herself difficult to approach, or refused the poet’s advances.
Wa-ālat ḥalfatan explicitly describes an oath. Lam taḥallal emphasizes that she did not attach a releasing qualification or exception. The mood differs from the playful dialogue of the preceding scene.