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 R’ Chisda — Rosh Hashanah 13a (verified).
זבת חלב ודבש — א״ר חסדא: למה ארץ ישראל נמשלה לצבי? לומר לך מה צבי זה קל מכל החיות\ldots
English: “Flowing with milk and honey” — R’ Chisda said: Why is the Land of Israel compared to a gazelle? To tell you that just as a gazelle is swifter than all other animals\ldots
Custom
Chazal link the distinctive praise of the Land to the image of the swift gazelle.