An-Nahl 16:66

وَإِنَّ لَكُمْ فِى ٱلْأَنْعَـٰمِ لَعِبْرَةً ۖ نُّسْقِيكُم مِّمَّا فِى بُطُونِهِۦ مِنۢ بَيْنِ فَرْثٍ وَدَمٍ لَّبَنًا خَالِصًا سَآئِغًا لِّلشَّـٰرِبِينَ

Wa-inna lakum fī l-anʿāmi laʿib'ratan nus'qīkum mimmā fī buṭūnihi min bayni farthin wadamin labanan khāliṣan sāighan lilshāribīna

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.