«وَلَمَّا أَحْضَرَ الْغُلَامُ مَا رَاحَ وَأَذْكَى بَيْنَنَا السِّرَاجَ تَأَمَّلْتُهُ»
When the servant brought what was at hand and brightened the lamp among us, I examined the visitor closely.
Adhkā al-sirāj means to brighten or kindle the lamp; taʾammaltuhu means to look at him attentively. Earlier the guests knew the stranger through his voice and verse; now the light reveals his face.
This is the narrative hinge: the moonlit evening, the knock and the courteous refusal all lead to a moment of recognition.