كَأَنَّ عُلُوبَ النَّسْعِ فِي دَأَيَاتِهَا
مَوَارِدُ مِنْ خَلْقَاءَ فِي ظَهْرِ قُرْدُدِ
The strap marks along her back are like channels where water collects or passes over smooth, hard rock in an elevated stony place.
ʿUlūb al-nasʿ are the marks caused by the strap fastening the riding equipment. They are compared with mawārid, channels or places that receive water in hard rock. The simile visualizes the lines and indentations on the camel’s tough back.