Demand for evidence and proof

أَمْ لَكُمْ سُلْطَـٰنٌ مُّبِينٌ

Or do you have a clear authority?

فَأْتُوا۟ بِكِتَـٰبِكُمْ إِن كُنتُمْ صَـٰدِقِينَ

Then produce your scripture, if you should be truthful.