«جَزَيْتُ مَنْ أَعْلَقَ بِي وُدَّهُ / جَزَاءَ مَنْ بَنَى عَلَى أُسِّهِ»
I repaid the person who attached his affection to me as one builds upon a firm foundation.
Aʿlaqa conveys attachment; uss is a foundation. Affection answered with affection becomes a building resting on solid ground.
The poet is not rejecting sincere friendship. His first verse says that genuine attachment deserves a genuine response, and the building image presents this as stable rather than impulsive.