When Fir'awn asked him about the Lord of Al-'Alamin, Musa said:

meaning, the Creator, Sovereign and Controller of all that, their God Who has no partner or associate. He is the One Who has created all things. He knows the higher realms and the heavenly bodies that are in them, both those that are stationary and those that move and shine brightly. He knows the lower realms and what is in them; the oceans, continents, mountains, trees, animals, plants and fruits. He knows what is in between the two realms; the winds, birds, and whatever is in the air. All of them are servants to Him, submitting and humbling themselves before Him.

means, if you have believing hearts and clear insight. At this, Fir'awn turned to the chiefs and leaders of his state around him, and said to them - mockingly expressing his disbelief in Musa:

{"Do you not hear?"} meaning, ‘are you not amazed by what this man is claiming - that you have another god other than me?’ Musa said to them:

meaning, the One Who created you and your forefathers, those who came before Fir'awn and his time.

{He said} that is, Fir'awn said:

meaning, there is no sense in his claim that there is any god other than me!

{(Musa) said } - to those in whose hearts Fir'awn had planted doubts:

‘He is the One Who made the east the place where the heavenly bodies rise, and made the west the place where they set; this is the system to which He has subjugated all the heavenly bodies, stationary and moving. If what Fir'awn claims is true, that he is your lord and your god, then let him turn things around so that the heavenly bodies set in the east and rise in the west.’ This is similar to the Ayah,

{who disputed with Ibrahim about his Lord, because Allah had given him the kingdom? When Ibrahim said: "My Lord is He Who gives life and causes death." He said, "I give life and cause death." Ibrahim said, "Verily, Allah brings the sun from the east. So cause it to rise from the west."} (2:258)

So when Fir'awn was defeated in debate, he resorted to the use of his force and power, believing that this would be effective in dealing with Musa, peace be upon him, so he said, as Allah tells us: