How Musa killed a Coptic Man
Having described Musa's beginnings, Allah then tells us that when he reached maturity, and was complete in stature, Allah gave him Hukm and religious knowledge. Mujahid said that this means prophethood.
وَكَذَلِكَ نَجْزِى الْمُحْسِنِينَ
(And thus do We reward the doers of good.) Then Allah describes how Musa reached the status that was decreed for him, that of Prophethood and speaking to Allah, as a direct consequence of killing the Coptic, which was the reason why he left Egypt and went to Madyan. Allah says:
وَدَخَلَ الْمَدِينَةَ عَلَى حِينِ غَفْلَةٍ مِّنْ أَهْلِهَا
(And he entered the city when its people were unaware.) Ibn Jurayj narrated from `Ata' Al-Khurasani, from Ibn `Abbas, "That was between Maghrib and `Isha'." Ibn Al-Munkadir narrated from `Ata' bin Yasar from Ibn `Abbas, "That was in the middle of the day." This was also the view of Sa`id bin Jubayr, `Ikrimah, As-Suddi and Qatadah.
فَوَجَدَ فِيهَا رَجُلَيْنِ يَقْتَتِلاَنِ
(and he found there two men fighting,) meaning, hitting one another and struggling with one another.
هَـذَا مِن شِيعَتِهِ
(one of his party, ) meaning, an Israelite,
وَهَـذَا مِنْ عَدُوِّهِ
(and the other of his foes.) meaning, a Coptic. This was the view of Ibn `Abbas, Qatadah, As-Suddi and Muhammad bin Ishaq. The Israelite man asked Musa, peace be upon him, for help, and Musa took advantage of the fact that people were not paying attention, so he went to the Coptic man and
فَوَكَزَهُ مُوسَى فَقَضَى عَلَيْهِ
(so Musa struck him with his fist and he died.) Mujahid said, "This means he punched him with his fist." And then he died.
قَالَ
(He said) refers to Musa.
وَدَخَلَ الْمَدِينَةَ عَلَى حِينِ غَفْلَةٍ مِّنْ أَهْلِهَا فَوَجَدَ فِيهَا رَجُلَيْنِ يَقْتَتِلاَنِ هَـذَا مِن شِيعَتِهِ وَهَـذَا مِنْ عَدُوِّهِ فَاسْتَغَـثَهُ الَّذِى مِن شِيعَتِهِ عَلَى الَّذِى مِنْ عَدُوِّهِ فَوَكَزَهُ مُوسَى فَقَضَى عَلَيْهِ قَالَ هَـذَا مِنْ عَمَلِ الشَّيْطَـنِ إِنَّهُ عَدُوٌّ مُّضِلٌّ مُّبِينٌ - قَالَ رَب إِنِّى ظَلَمْتُ نَفْسِى فَاغْفِرْ لِى فَغَفَرَ لَهُ إِنَّهُ هُوَ الْغَفُورُ الرَّحِيمُ قَالَ رَبِّ بِمَآ أَنْعَمْتَ عَلَىَّ
("This is of Shaytan's doing, verily, he is a plain misleading enemy." He said: "My Lord! Verily, I have wronged myself, so forgive me." Then He forgave him. Verily, He is the Oft-Forgiving, the Most Merciful. He said: "My Lord! For that with which You have favored me,) meaning, `what You have given me of prestige, power and blessings -- '
فَلَنْ أَكُونَ ظَهِيراً
(I will nevermore be a helper of the criminals!) `those who disbelieve in You and go against Your commands.'
Tafsir Ibn Kathir (abridged, English).