The Command to eat Pure Things and the Explanation of the Prohibited Things
Allah commands;
يَا أَيُّهَا الَّذِينَ امَنُواْ كُلُواْ مِن طَيِّبَاتِ مَا رَزَقْنَاكُمْ وَاشْكُرُواْ لِلّهِ إِن كُنتُمْ إِيَّاهُ تَعْبُدُونَ
O you who believe (in the Oneness of Allah ـ Islamic Monotheism)! Eat of the lawful things that We have provided you with, and be grateful to Allah, if it is indeed He Whom you worship.
Allah commands His believing servants to eat from the pure things that He has created for them and to thank Him for it, if they are truly His servants.
Eating from pure sources is a cause for the acceptance of supplications and acts of worship, just as eating from impure sources prevents the acceptance of supplications and acts of worship, as mentioned in a Hadith recorded by Imam Ahmad, that Abu Hurayrah said that Allah's Messenger said;
يأَيُّهَا النَّاسُ إِنَّ اللهَ طَيِّبٌ لَا يَقْبَلُ إِلاَّ طَيِّـبًا وَإنَّ اللهَ أَمَرَ الْمُوْمِنِينَ بِمَا أَمَرَ بِهِ الْمُرْسَلِينَ فَقَالَ
O people! Allah is Tayyib (Pure and Good) and only accepts that which is Tayyib. Allah has indeed commanded the believers with what He has commanded the Messengers, for He said;
يأَيُّهَا الرُّسُلُ كُلُواْ مِنَ الطَّيِّبَـتِ وَاعْمَلُواْ صَـلِحاً إِنِّى بِمَا تَعْمَلُونَ عَلِيمٌ
O (you) Messengers! Eat of the Tayyibat and do righteous deeds. Verily, I am well-acquainted with what you do. (23;51),
and;
يَا أَيُّهَا الَّذِينَ امَنُواْ كُلُواْ مِن طَيِّبَاتِ مَا رَزَقْنَاكُمْ
O you who believe! Eat of the lawful things that We have provided you with.
ثُمَّ ذَكَرَ الرَّجُلَ
He then mentioned a man,
يُطِيلُ السَّفَرَ أَشْعَثَ أَغْبَرَ يَمُدُّ يَدَيْهِ إِلَى السَّمَاءِ يَا رَبِّ يَا رَبِّ وَمَطْعَمُهُ حَرَامٌ وَمَشْرَبُهُ حَرَامٌ وَملْبَسُهُ حَرَامٌ وَغُذِّيَ بالْحَرَامِ فَأَنَّى يُسْتَجَابُ لِذلِكَ
who is engaged in a long journey, whose hair is untidy and who is covered in dust, he raises his hands to the sky, and says, `O Lord! O Lord!' Yet, his food is from the unlawful, his drink is from the unlawful, his clothes are from the unlawful, and he was nourished by the unlawful, so how can it (his supplication) be accepted?"
It was also recorded by Muslim and At-Tirmidhi
After Allah mentioned how He has blessed His creatures by providing them with provisions, and after commanding them to eat from the pure things that He has provided them, He then stated that He has not prohibited anything for them, except dead animals