«طَوَى بُرَى أَعْظُمَهُ لَمَّا انْبَرَى»
Hunger has worn away his very bones as he became wasted and weak.
Ṭawā denotes going hungry; burā suggests grinding or wearing something down; aʿẓum means bones.
The encounter now reverses expectations. Abū Zayd knocked in search of help for his hunger, but the youth answering the door describes hunger of his own. The surprise is a turn in the dialogue itself, not merely a rhetorical ornament.