كَدَأْبِكَ مِنْ أُمِّ الْحُوَيْرِثِ قَبْلَهَا
وَجَارَتِهَا أُمِّ الرَّبَابِ بِمَأْسَلِ
It is as your familiar experience was previously with Umm al-Ḥuwayrith, and with her neighbor Umm al-Rabāb at Maʾsal.
Daʾb denotes a habitual practice or recurrent pattern. The poet connects his present distress with earlier experiences: the same longing, disappointment in love, and emotional suffering have occurred before.
The point depends on the previous verses. Ka-daʾbika does not introduce an unrelated theme; it recalls precedents for the sorrow already expressed.