فَطَوْرًا بِهِ خَلْفَ الزَّمِيلِ وَتَارَةً
عَلَى حَشَفٍ كَالشَّنِّ ذَاوٍ مُجَدَّدِ
At times the tail moves behind the rider; at others it strikes her shrunken teats, likened to a worn, dried-out and cut leather water-skin.
Fa-ṭawran ... wa-tāratan sets up two alternating actions. First the tail moves behind the person riding; then it touches the rear of the animal.
Ḥashaf suggests a shrunken condition, while al-shann is an old, dried leather water-skin. The comparison is deliberately concrete rather than conventionally flattering: the poet observes actual bodily detail while preserving the mount’s worth as a traveler.