Al-Qur'an Surah Ash-Shu'ara Verse 23

Pharaoh said, to Moses, `And what is "the Lord of the Worlds" ', the One Whose Messenger you say you indeed are? In other words; what exactly is He? And since there is no way for creation to know the true nature of God, but only to know Him through [an articulation of] His attributes, Moses, blessings and peace be upon him, responds to him with [mention of] some of these [attributes];

Tafseer Ibn Kathir

Allah tells us about the disbelief, rebellion, oppression and denial of Fir`awn

He tells;

قَالَ فِرْعَوْنُ وَمَا رَبُّ الْعَالَمِينَ

(Fir`awn) said;"And what is the Lord of the `Alamin!"

This is because he used to say to his people;

مَا عَلِمْتُ لَكُمْ مِّنْ إِلَـهٍ غَيْرِى

I know not that you have a god other than me. (28;38)

فَاسْتَخَفَّ قَوْمَهُ فَأَطَاعُوهُ

Thus he fooled his people, and they obeyed him. (43;54)

They used to deny the Creator, may He be glorified, and they believed that they had no other lord than Fir`awn.

When Musa said to them;"I am the Messenger of the Lord of the worlds," Fir`awn said to him, "Who is this who you are claiming is the Lord of Al-`Alamin other than me!"

This is how it was interpreted by the scholars of the Salaf and the Imams of later generations.

As-Suddi said,

"This Ayah is like the Ayah,

قَالَ فَمَن رَّبُّكُمَا يمُوسَى

قَالَ رَبُّنَا الَّذِى أَعْطَى كُلَّ شَىءٍ خَلْقَهُ ثُمَّ هَدَى

(Fir`awn) said;"Who then, O Musa, is the Lord of you two!"

He said;"Our Lord is He Who gave to each thing its form and nature, then guided it aright." (20;49-50)

Those among the philosophers and others who claimed that this was a question about the nature or substance (of Allah) are mistaken.

Fir`awn did not believe in the Creator in the first place, so he was in no position to ask about the nature of the Creator; he denied that the Creator existed at all, as is apparent from the meaning, even though proof and evidence had been established against him.
When Fir`awn asked him about the Lord of Al-`Alamin, Musa said