An-Nahl - 16:66

وَإِنَّ لَكُمْ فِي الأَنْعَامِ لَعِبْرَةً نُّسْقِيكُم مِّمَّا فِي بُطُونِهِ مِن بَيْنِ فَرْثٍ وَدَمٍ لَّبَنًا خَالِصًا سَآئِغًا لِلشَّارِبِينَ
[16:66]
And most surely there is a lesson for you in the cattle; We give you to drink of what is in their bellies-- from betwixt the feces and the blood-- pure milk, easy and agreeable to swallow for those who drink.
And verily in cattle (too) will ye find an instructive sign. From what is within their bodies between excretions and blood, We produce, for your drink, milk, pure and agreeable to those who drink it.
And lo! in the cattle there is a lesson for you. We give you to drink of that which is in their bellies, from betwixt the refuse and the blood, pure milk palatable to the drinkers.