Then we will surely bring you magic like it, so make between us and you an appointment, which we will not fail to keep and neither will you, in a place assigned."
Fir`awn describes Musa's Proofs as being Magic and Their Agreement to hold a Contest
Allah, the Exalted, informs of what Fir`awn said to Musa when he showed him the great proof. This great sign to Fir`awn was Musa casting down his stick which became a huge snake, and his pulling his hand out from under his arm while it was glowing white without any illness. At this, Fir`awn said, "This is magic that you have brought to us to bewitch us and conquer the people, so that they will follow you. Then you will outnumber us." Fir`awn then said, "Your plan will not work. We have magic just like yours, so do not let yourself be deceived by that what you are doing."
By words مَكَانًا سُوًى(at an even place) in verse 58 the Pharaoh proposed that the contest between Sayyidna Musa (علیہ السلام) and his own magicians should be held at a place which should, as far as possible, be within easy access of the Egyptians, Sayyidna Musa (علیہ السلام) and the Bani Isra'il. The latter readily accepted this proposal and fixed the day and the time for the contest by suggesting۔
Tazkirul Quran
Maulana Wahiduddin KhanOn ayahs 58–60
Moses continued to preach to Pharaoh over a long period of time, using rational arguments and also showing him miracles of a physical nature. But Pharaoh did not believe in Moses. In reality, admitting the truth of Moses’s preaching would have amounted to a negation of himself—something which his proud and egoistic mentality would never permit. Pharaoh tried to nullify Moses’s rational arguments by means of irrelevant pleas. On the subject of his miracles, Pharaoh alleged that they were simply magic, i.e., something which had no relevance to God, and insisted that anybody could acquire the necessary expertise to perform such feats. In order to keep up his boastful assertions, he said that he, through his magicians, could perform the same feats or miracles as Moses had demonstrated. After some discussion, it was finally decided that, at the forthcoming national fair, magicians of the country should gather, and there should be a competition between them and Moses before all the people.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.