Parashas Shemos
וָאֵרֵ֞ד לְהַצִּיל֣וֹ ׀ מִיַּ֣ד מִצְרַ֗יִם וּֽלְהַעֲלֹתוֹ֮ מִן־הָאָ֣רֶץ הַהִוא֒ אֶל־אֶ֤רֶץ טוֹבָה֙ וּרְחָבָ֔ה אֶל־אֶ֛רֶץ זָבַ֥ת חָלָ֖ב וּדְבָ֑שׁ אֶל־מְק֤וֹם הַֽכְּנַעֲנִי֙ וְהַ֣חִתִּ֔י וְהָֽאֱמֹרִי֙ וְהַפְּרִזִּ֔י וְהַחִוִּ֖י וְהַיְבוּסִֽי׃
I have come down to rescue them from the Egyptians and to bring them out of that land to a good and spacious land, a land flowing with milk and honey, the region of the Canaanites, the Hittites, the Amorites, the Perizzites, the Hivites, and the Jebusites.
Torah Temimah points to TT / Chullin (verified).
ארץ זבת חלב — מלמד שהחלב מותר משום אבר מן החי.
English: “A land flowing with milk” — this teaches that milk is permitted [and is not forbidden] as a limb from a living animal.
Custom
Chazal derive from the praise of “flowing milk” that ordinary milk is not classified as eiver min hachai.