נֹ֛פֶת תִּטֹּ֥פְנָה שִׂפְתוֹתַ֖יִךְ כַּלָּ֑ה דְּבַ֤שׁ וְחָלָב֙ תַּ֣חַת לְשׁוֹנֵ֔ךְ וְרֵ֥יחַ שַׂלְמֹתַ֖יִךְ כְּרֵ֥יחַ לְבָנֽוֹן׃ (ס)
Thy lips, O my bride, drop honey— Honey and milk are under thy tongue; And the smell of thy garments is like the smell of Lebanon.
Kol Bo
There is also a custom of eating honey and milk on Shavuot because the Torah is compared to honey and milk as it is written "honey and milk under your tongue" (Songs 4:11)