Yoma8: 2
הָאוֹכֵל כְּכוֹתֶבֶת הַגַּסָּה — כָּמוֹהָ וּכְגַרְעִינָתָהּ — וְהַשּׁוֹתֶה מְלֹא לֻגְמָיו חַיָּב. כָּל הָאֹכָלִין מִצְטָרְפִין לְכַכּוֹתֶבֶת, וְכָל הַמַּשְׁקִין מִצְטָרְפִין לִמְלֹא לֻגְמָיו, הָאוֹכֵל וְשׁוֹתֶה אֵין מִצְטָרְפִין.
One who eats the volume of a large date —- like it and its pit —- or who drinks [the volume of] both his full cheeks is liable [for punishment]. All foods combine for the volume of a date, and all drinks combine for the volume of his cheekfuls, but food and drink do not combine.