Surah An-Nahl, ayah 66

16:66

وَإِنَّ لَكُمۡ فِي ٱلۡأَنۡعَٰمِ لَعِبۡرَةٗۖ نُّسۡقِيكُم مِّمَّا فِي بُطُونِهِۦ مِنۢ بَيۡنِ فَرۡثٖ وَدَمٖ لَّبَنًا خَالِصٗا سَآئِغٗا لِّلشَّٰرِبِينَ ٦٦

Wa inna lakum fil-an'āmi la'ibratan nusqīkum mimmā fī butūnihī mim bayni farthin wadamil labanan khālisan sā'ighal lish-shāribīn

And indeed, for you in grazing livestock is a lesson. We give you drink from what is in their bellies - between excretion and blood - pure milk, palatable to drinkers.