Imam Ali (peace be upon him): Allah revealed the Quran in seven categories: ... and among the Quran are verses in which Allah the Exalted explained the cause of the survival of creation, the means of their livelihood and its varieties ... As for the cause by which creation subsists, Allah the Mighty and Majestic explained in His Book that the survival of creation arises from four things: food, drink, clothing and shelter, and marriages for procreation; and in all of these there is need of command and prohibition [from Allah]. As for foods, they are from the categories of plants and of the cattle whose flesh is lawful. Allah the Exalted said concerning plants: أَنَّا صَبَبْنَا الْماءَ صَبًّا ثُمَّ شَقَقْنَا الْأَرْضَ شَقًّا فَأَنْبَتْنا فِیها حَبًّا وَ عِنَباً وَ قَضْباً وَ زَیْتُوناً وَ نَخْلًا وَ حَدائِقَ غُلْباً وَ فاکِهَةً وَ أَبًّا مَتاعاً لَکُمْ وَ لِأَنْعامِکُمْ [Indeed, We poured down the water abundantly, then We split the earth into fissures and caused to grow within it grain, and grapes and green herbs, and olives and palm trees, and lush enclosed gardens, and fruits and herbage — a provision for you and for your cattle].