This is a statement of permission from Allah, for His servants, allowing them to eat the slaughtered animals werein His Name was mentioned when slaughtering them. It is understood from it that He has not allowed that over which Allah's Name was not mentioned when slaughtering. This was the practice of the pagans of Quraysh who used to eat dead animals and eat what was slaughtered for the idols. Allah next encourages eating from the meat of sacrificed animals on which His Name was mentioned upon slaughtering,

﴿وَمَا لَكُمْ أَلاَّ تَأْكُلُواْ مِمَّا ذُكِرَ اسْمُ اللَّهِ عَلَيْهِ وَقَدْ فَصَّلَ لَكُم مَّا حَرَّمَ عَلَيْكُمْ﴾

(And why should you not eat of that on which Allah's Name has been mentioned, while He has explained to you what is forbidden to you...) meaning, He has explained and made clear to you what He has prohibited for you in detail,

﴿إِلاَّ مَا اضْطُرِرْتُمْ إِلَيْهِ﴾

(except under compulsion of necessity.) In which case, you are allowed to eat whatever you can find. Allah next mentions the ignorance of the idolators in their misguided ideas, such as eating dead animals and what was sacrificed while other than Allah's Name was mentioned when slaughtering them. Allah said,

﴿وَإِنَّ كَثِيرًا لَّيُضِلُّونَ بِأَهْوَائِهِم بِغَيْرِ عِلْمٍ إِنَّ رَّبَّكَ هُوَ أَعْلَمُ بِالْمُعْتَدِينَ﴾

(And surely, many do lead astray by their own desires through lack of knowledge. Certainly your Lord knows best the transgressors.) He has complete knowledge of their transgression, lies and inventions.

﴿وَذَرُواْ ظَـهِرَ الإِثْمِ وَبَاطِنَهُ إِنَّ الَّذِينَ يَكْسِبُونَ الإِثْمَ سَيُجْزَوْنَ بِمَا كَانُواْ يَقْتَرِفُونَ ﴾

(120. Leave sin, open and secret. Verily, those who commit sin will get due recompense for that which they used to commit.) Mujahid said that,

﴿وَذَرُواْ ظَـهِرَ الإِثْمِ وَبَاطِنَهُ﴾

(Leave evil, open and secret...) refers to all kinds of sins committed in public and secret. Qatadah said that,

﴿وَذَرُواْ ظَـهِرَ الإِثْمِ وَبَاطِنَهُ﴾

(Leave sin, open and secret...) encompasses sins committed in public and secret, whether few or many. In another statement, Allah said,

﴿قُلْ إِنَّمَا حَرَّمَ رَبِّيَ الْفَوَحِشَ مَا ظَهَرَ مِنْهَا وَمَا بَطَنَ﴾

(Say: "(But) the things that my Lord has indeed forbidden are Al-Fawahish (evil sins) whether committed openly or secretly.) ﴿7:33﴾ This is why Allah said,

﴿إِنَّ الَّذِينَ يَكْسِبُونَ الإِثْمَ سَيُجْزَوْنَ بِمَا كَانُواْ يَقْتَرِفُونَ﴾

(Verily, those who commit sin will get due recompense for that which they used to commit.) Whether the sins they committed were public or secret, Allah will compensate them for these sins. Ibn Abi Hatim recorded that An-Nawwas bin Sam`an said, "I asked Allah's Messenger about Al-Ithm. He said,

«الْإِثمُ مَا حَاكَ فِي صَدْرِكَ وَكَرِهْتَ أَنْ يَطَّلِعَ النَّاسُ عَلَيْه»

(The sin is that which you find in your heart and you dislike that people become aware of it.)

﴿وَلاَ تَأْكُلُواْ مِمَّا لَمْ يُذْكَرِ اسْمُ اللَّهِ عَلَيْهِ وَإِنَّهُ لَفِسْقٌ وَإِنَّ الشَّيَـطِينَ لَيُوحُونَ إِلَى أَوْلِيَآئِهِمْ لِيُجَـدِلُوكُمْ وَإِنْ أَطَعْتُمُوهُمْ إِنَّكُمْ لَمُشْرِكُونَ ﴾

(121. Eat not of that on which Allah's Name has not been pronounced, for surely it is disobedience. And certainly, the Shayatin do inspire their friends to dispute with you, and if you obey them, then you would indeed be polytheists.)