Tafsir of Ta-Ha 20:59

31

The object of Pharaoh was this: "Once the sorcerers are able to transform the staffs and ropes into serpents, the entire effect of the miracle performed by Moses would disappear from the people's minds. That was exactly to Moses' advantage, who suggested that it was no good fixing an ordinary day or place for the purpose. The Day of the Feast was at hand. People would flock on that occasion from all corners of the empire. Therefore, the encounter should be held in the open so that all might witness it, and in the day time so that every one should be able to see it clearly."