In The Name of Allaah, The Most Merciful, The Bestower of Mercy
Allaah [The Most High] said:
يَسۡـَٔلُونَكَ مَاذَآ أُحِلَّ لَهُمۡۖ قُلۡ أُحِلَّ لَكُمُ ٱلطَّيِّبَـٰتُۙ وَمَا عَلَّمۡتُم مِّنَ ٱلۡجَوَارِحِ مُكَلِّبِينَ تُعَلِّمُونَہُنَّ مِمَّا عَلَّمَكُمُ ٱللَّهُۖ فَكُلُواْ مِمَّآ أَمۡسَكۡنَ عَلَيۡكُمۡ وَٱذۡكُرُواْ ٱسۡمَ ٱللَّهِ عَلَيۡهِۖ وَٱتَّقُواْ ٱللَّهَۚ إِنَّ ٱللَّهَ سَرِيعُ ٱلۡحِسَابِ
They ask you [O Muhammad)]what is lawful for them [as food]. Say: ‘’Lawful unto you are At-Tayyibat [all kind of Halal (lawful-good) foods which Allah has made lawful (meat of slaughtered eatable animals, milk products, fats, vegetables and fruits, etc.)]. And those beasts and birds of prey which you have trained as hounds, training and teaching them [to catch] in the manner as directed to you by Allaah; so eat of what they catch for you, but pronounce the Name of Allah over it, and fear Allah. Verily, Allah is Swift in reckoning.’’ [Surah Al-Maa’idah. Aayah 4]
Imaam Ibnul Qayyim [rahimahullaah] said: Indeed, Allaah [Glorified be He] declared the prey of the untrained hound a dead meat and unlawful to eat, and He declared lawful the prey of the trained hound. This is from that which shows the nobility of knowledge, because Allaah did not declare lawful except the prey of the trained hound. Had it not been that knowledge and teaching have a special distinguished virtue and nobility, the trained and untrained hound would have been the same.
[An Excerpt Mihtaah Daarus Sa’aadah. 1/55. Slightly paraphrased]