Tafsir of Al-A'raf 7:106

(He said) is an explanatory resumption, as if it were said: "What did Pharaoh say?" So it was said: He said: (If you have come with a sign) from the One who sent you, as you claim, (then bring it), meaning: produce it before me so that your truthfulness in your claim may be proven by it. The distinction between the condition and the recompense is something beyond reproach, and perhaps the matter is sufficient without needing to insist upon that, as it is achieved through what I do not think is hidden from you. (If you are of the truthful) in your claim, for being among those known for truthfulness necessitates the demonstration of a sign, inevitably.