Concerning his statement,

﴿قَدْ جِئْنَـكَ بِـَايَةٍ مِّن رَّبِّكَ﴾

(indeed, We have come with a sign from your Lord!) meaning with evidence and a miracle from your Lord.

﴿وَالسَّلَـمُ عَلَى مَنِ اتَّبَعَ الْهُدَى﴾

(And peace will be upon him who follows the guidance!) meaning, `peace be upon you if you follow the guidance.' Because of this, when the Messenger of Allah wrote a letter to Heraclius, the emperor of Rome, beginning with,

«بِسْمِ اللهِ الرَّحْمنِ الرَّحِيمِ، مِنْ مُحَمَّدٍ رَسُولِ اللهِ إِلَى هِرَقْلَ عَظِيمِ الرُّومِ، سَلَامٌ عَلَى مَنِ اتَّبَعَ الْهُدى، أَمَّا بَعْدُ، فَإِنِّي أَدْعُوكَ بِدِعَايَةِ الْإِسْلَامِ، فَأَسْلِمْ تَسْلَمْ يُؤْتِكَ اللهُ أَجْرَكَ مَرَّتَيْن»

(In the Name of Allah, the Most Gracious, the Most Merciful. From Muhammad, the Messenger of Allah, to Heraclius the emperor of Rome. Peace be upon him who follows the guidance. Thus, to proceed: Verily, I invite you with the invitation of Islam. So accept Islam and you will be safe, and Allah will give you a double reward.) Due to this, Musa and Harun said to Fir`awn,

﴿فَأْتِيَاهُ فَقُولاَ إِنَّا رَسُولاَ رَبِّكَ فَأَرْسِلْ مَعَنَا بَنِى إِسْرَءِيلَ وَلاَ تُعَذِّبْهُمْ قَدْ جِئْنَـكَ بِـَايَةٍ مِّن رَّبِّكَ وَالسَّلَـمُ عَلَى مَنِ اتَّبَعَ الْهُدَى - إِنَّا قَدْ أُوحِىَ إِلَيْنَآ أَنَّ الْعَذَابَ عَلَى مَن كَذَّبَ وَتَوَلَّى ﴾

(And peace will be upon him who follows the guidance! Truly, it has been revealed to us that the torment will be for him who denies, and turns away.) In His flawless revelation, Allah has revealed to us that torment is prepared exclusively for those who reject the signs of Allah and turn away from His obedience. As Allah says,

﴿فَأَمَّا مَن طَغَى - وَءاثَرَ الْحَيَوةَ الدُّنْيَا - فَإِنَّ الْجَحِيمَ هِىَ الْمَأْوَى ﴾

(Then for him who transgressed all bounds, and preferred the life of this world, Verily, his abode will be Hellfire.) ﴿79:37-39﴾ Allah, the Exalted, also says,

﴿فَأَنذَرْتُكُمْ نَاراً تَلَظَّى - لاَ يَصْلَـهَآ إِلاَّ الاٌّشْقَى - الَّذِى كَذَّبَ وَتَوَلَّى ﴾

(Therefore I have warned you of a blazing Fire. None shall enter it save the most wretched. Who denies and turns away.) ﴿92:14-16﴾ Allah also says,

﴿فَلاَ صَدَّقَ وَلاَ صَلَّى - وَلَـكِن كَذَّبَ وَتَوَلَّى ﴾

(So he neither believed nor prayed! But on the contrary, he belied and turned away.) ﴿75:31-32﴾ This means that he denied with his heart and turned away by his actions.

﴿قَالَ فَمَن رَّبُّكُمَا يمُوسَى - قَالَ رَبُّنَا الَّذِى أَعْطَى كُلَّ شَىءٍ خَلْقَهُ ثُمَّ هَدَى - قَالَ فَمَا بَالُ الْقُرُونِ الاٍّولَى - قَالَ عِلْمُهَا عِندَ رَبِّى فِى كِتَـبٍ لاَّ يَضِلُّ رَبِّى وَلاَ يَنسَى ﴾

(49. Fir`awn said: "Who then, O Musa, is the Lord of you two'') (50. ﴿Musa﴾ said: "Our Lord is He Who gave to each thing its form and nature, then guided it aright.'') (51. ﴿Fir`awn﴾ said: "What about the generations of old'') (52. ﴿Musa﴾ said: "The knowledge thereof is with my Lord, in a Record. My Lord neither errs nor forgets.''