وَقَالَ مُوسَى يَفِرْعَوْنُ إِنَّى رَسُولٌ مِّن رَّبِّ الْعَـلَمِينَ
(And Musa said: "O Fir`awn! Verily, I am a Messenger from the Lord of all that exists".) meaning Musa said, `the one Who sent me is the Creator, Lord and King of all things,'
حَقِيقٌ عَلَى أَن لاَ أَقُولَ عَلَى اللَّهِ إِلاَّ الْحَقَّ
("Proper it is for me that I say nothing concerning Allah but the truth. ") `It is incumbent and a duty for me to convey only the Truth from Him, because of what I know of His might and power.'
قَدْ جِئْتُكُمْ بِبَيِّنَةٍ مِّن رَّبِّكُمْ
("Indeed I have come unto you from your Lord with a clear proof.") `I brought unequivocal evidence that Allah gave me to prove that I am conveying the truth to you,'
فَأَرْسِلْ مَعِىَ بَنِى إِسْرَءِيلَ
("So let the Children of Israel depart along with me.") means, release them from your slavery and subjugation. Let them worship your Lord and their Lord. They are from the offspring of an honorable Prophet, Isra'il, who is Ya`qub son of Ishaq son of Ibrahim, the Khalil (intimate friend) of Allah.
قَالَ إِن كُنتَ جِئْتَ بِـَايَةٍ فَأْتِ بِهَآ إِن كُنتَ مِنَ الصَّـدِقِينَ
(Fir`awn said: "If you have come with a sign, show it forth, if you are one of those who tell the truth.") Fir`awn said, `I will not believe in what you have said nor entertain your request'. Therefore, he said, `if you have proof, then produce it for us to see, so that we know if your claim is true.'
Ma'arif al-Qur'an
Mufti Muhammad Shafi
The verse is a clear declaration of the prophet Musa (علیہ السلام) before Pharaoh that he was a messenger of Allah, the Lord of all the worlds, and that his status of prophethood does not allow him to ascribe anything but truth to Allah because the message given to the prophets by Allah is a sacred trust and it is a great sin to tamper with it. All the prophets of Allah are free of all sins and cannot do so. The prophet Musa (علیہ السلام) tried to convince them that they should believe him because his truthfulness was beyond question and that he had never uttered a word of lie. In addition to this, his miracles are a clear proof to support his claim to prophethood.
God has blessed man with the powers of observation, hearing and thinking, so that he may learn lessons and, with their help, may understand the signs of God. But when a man does not utilize these powers for the purpose for which they were intended, then it inevitably happens that the sensitivity of his heart starts waning until his feelings become blunted; the seal of insensitivity is thus fixed on his heart and mind. Now, his position becomes that of one who does not see in spite of having eyes, does not hear in spite of having ears and does not understand in spite of having a mind; and in spite of being a human being, he loses his humanity. The human race began with the followers of Adam. Thereafter, when they fell into wrong ways, the prophets of God came to admonish them. Now those who reformed themselves on the advent of the prophets were saved and those who refused to be reformed were destroyed. Again the following generations forgot the vows of submission to God made to their prophets, and they suffered the same consequences as those of the later generations of Adam’s followers. Such a state of affairs has occurred again and again, so much so that the history of the greater part of the human race has become that of disobedience and the breaking of pledges.
Uthmani text of the Madinah mushaf (King Fahd Complex). Translation: Saheeh International. Tafsir via Quran.com.