«إِنْ رَغِبْتِ فِي الْمَشُوفِ الْمُعَلَّمِ»
If you desire the polished, marked coin.
The polished, marked coin is described to increase the attendant’s desire to answer. Al-Ḥārith uses a financial incentive to obtain a clue about the elder’s identity.
Buying information is not the same as verifying it. Payment can shape what a source says, so corroborating observation remains important. The episode separates the means of eliciting a response from the grounds for believing it.