He said: "My Lord! I have killed a man among them, and I fear that they will kill me. (33)"And my brother Harun – he is more eloquent in speech than me, so send him with me as a helper to confirm me. Verily, I fear that they will deny me. (34)Allah said: "We will strengthen your arm through your brother, and give you both power, so they shall not be able to harm you, with Our Ayat; you two as well as those who follow you, will be the victors. (35)

When Allah commanded him to go to Fir'awn, the one who he had run away from and whose vengeance he feared,

قَالَ رَبِّ إِنِّي قَتَلْتُ مِنْهُمْ نَفْسًا

(Musa said: My Lord! I have killed a man among them,) meaning, that Coptic,

فَأَخَافُ أَنْ يَقْتُلُونِ

(and I fear that they will kill me.) i.e., 'when they see me.'

وَأَخِي هَارُونُ هُوَ أَفْصَحُ مِنِّي لِسَانًا 

(And my brother Harun – he is more eloquent in speech than me,) Musa, peace be upon him, had a speech defect, because when he had been given the choice between a date and a pearl, he mistakenly picked up a coal and placed it on his tongue, so he found it difficult to speak clearly. Musa said:

وَاحْلُلْ عُقْدَةً مِنْ لِسَانِي - يَفْقَهُوا قَوْلِي - وَاجْعَلْ لِي وَزِيرًا مِنْ أَهْلِي - هَارُونَ أَخِي - اشْدُدْ بِهِ أَزْرِي - وَأَشْرِكْهُ فِي أَمْرِي

("And loose the knot (the defect) from my tongue. That they understand my speech. And appoint for me a helper from my family, Harun, my brother. Increase my strength with him, And let him share my task.")(20:27-32) meaning, 'give me someone to keep me company in this immense task of prophethood and conveying the Message to this arrogant, tyrannical and stubborn king.' Hence Musa said:

وَأَخِي هَارُونُ هُوَ أَفْصَحُ مِنِّي لِسَانًا فَأَرْسِلْهُ مَعِيَ رِدْءًا

(And my brother Harun – he is more eloquent in speech than me: so send him with me as a helper) meaning, as a support to give strength to my cause and confirm what I say and convey from Allah, because the word of two carries more weight in people's minds than the word of one. So he said:

إِنِّي أَخَافُ أَنْ يُكَذِّبُونِ

(Verily, I fear that they will deny me.) Muhammad bin Ishaq said:

رِدْءًا يُصَدِّقُنِي

(as a helper to confirm me.) means, 'to explain to them what I say, for he can understand me where they may not.' When Musa asked for this, Allah said to him:

سَنَشُدُّ عَضُدَكَ بِأَخِيكَ

(We will strengthen your arm through your brother,) meaning, 'We will add strength to your cause and give you help through your brother, who you have asked to be made a Prophet alongside you.' This is like the Ayat;

قَدْ أُوتِيتَ سُؤْلَكَ يَا مُوسَىٰ

(You are granted your request, O Musa!)(20:36)

وَوَهَبْنَا لَهُ مِنْ رَحْمَتِنَا أَخَاهُ هَارُونَ نَبِيًّا 

(And We granted him his brother Harun, (also) a Prophet, out of Our mercy)(19:53). One of the Salaf said, "There is no one who has ever done a greater favor to his brother than Musa did for Harun, may peace be upon them both, for he interceded for him until Allah made him a Prophet and Messenger with him to Fir'awn and his chiefs. Allah said concerning Musa:

وَكَانَ عِنْدَ اللَّهِ وَجِيهًا

(he was honorable before Allah)(33:69).

وَنَجْعَلُ لَكُمَا سُلْطَانًا 

(and (We will) give you both power) means, overwhelming evidence.

فَلَا يَصِلُونَ إِلَيْكُمَا ۚ بِآيَاتِنَا

(so they shall not be able to harm you, with Our Ayat;) means, 'they will have no way or means of harming you because you are conveying the signs of Allah.' This is like the Ayat:

يَا أَيُّهَا الرَّسُولُ بَلِّغْ مَا أُنْزِلَ إِلَيْكَ مِنْ رَبِّكَ ۖ 

(O Messenger! Proclaim (the Message) which has been sent down to you from your Lord.) until His saying:

وَاللَّهُ يَعْصِمُكَ مِنَ النَّاسِ ۗ 

(Allah will protect you from mankind)(5:67).

الَّذِينَ يُبَلِّغُونَ رِسَالَاتِ اللَّهِ

(Those who convey the Message of Allah) until His saying:

وَكَفَىٰ بِاللَّهِ حَسِيبًا

(And sufficient is Allah as a Reckoner)(33:39). And sufficient is Allah as a Helper and Supporter. And Allah told them the consequences in this world and the next, for them and for those who followed them,

أَنْتُمَا وَمَنِ اتَّبَعَكُمَا الْغَالِبُونَ

(you two as well as those who follow you will be the victors.) This is like the Ayat:

كَتَبَ اللَّهُ لَأَغْلِبَنَّ أَنَا وَرُسُلِي ۚ إِنَّ اللَّهَ قَوِيٌّ عَزِيزٌ

(Allah has decreed: "Verily, it is I and My Messengers who shall be the victorious." Verily, Allah is All-Powerful, All-Mighty.)(58:21)

إِنَّا لَنَنْصُرُ رُسُلَنَا وَالَّذِينَ آمَنُوا فِي الْحَيَاةِ الدُّنْيَا

(Verily, We will indeed make victorious Our Messengers and those who believe in this world's life)(40:51) to the end of the Ayah.