قَرَنْتُ بِالرُّقْعَةِ دِرْهَمًا وَقِطْعَةً
I added a dirham and a piece to the slip.
A missing slip creates a dispute; al-Ḥārith offers a dirham to learn the hidden explanation. He moves from detached observer to participant in the exchange.
The coin is a narrative instrument. It opens a conversation and prepares the identity reveal. But paying for an explanation is not equivalent to possessing the facts. The reader must still distinguish the narrator’s initiative from the information that comes only through subsequent speech.