أَصْدِقَانِي سِنَّ بَكْرِكُمَا، وَلَكُمَا الْأَمَانُ مِنْ تَبِعَةِ مَكْرِكُمَا
Tell me the truth of your scheme, and you have safety from the consequences of your trick.
The judge says aṣdiqānī to both participants and promises wa-lakumā al-amān. The reassurance changes the incentives: he seeks a truthful statement rather than provoking further defensive performance.
Aṣdiqānī addresses two people, not one. The phrase about the consequences of their trick shows what the judge suspects, but he is still seeking their admission. The assurance facilitates inquiry; it is not itself proof of what happened.
Practice: Why offer safety? To encourage both parties to disclose the scheme.