Ash-Shu'ara' - 26:31

قَالَ فَأْتِ بِهِ إِن كُنتَ مِنَ الصَّادِقِينَ
[26:31]
Said he: Bring it then, if you are of the truthful ones.
(Pharaoh) said: "Show it then, if thou tellest the truth!"
(Pharaoh) said: Produce it then, if thou art of the truthful!