Yoma 80B

כי אתשיל, בעוג מלך הבשן אתשיל, דהוו להו בית שמאי לחומרא.

When this question with regard to the measure of liquid was asked, it was not asked about an average-sized person, for whom a mouthful is smaller than 1/4th-log. Rather, the question was asked even about Og, king of Bashan, in which case, it is Beit Shammai who are stringent, for Og’s cheekful is much more than 1/4th-log.

מתקיף לה רבי זירא: מאי שנא אכילה, דכל חד וחד ⁠— בככותבת, ומאי שנא שתיה, דכל חד וחד בדידיה? אמר ליה אביי: קים להו לרבנן בככותבת, דבהכי מיתבא דעתיה, בציר מהכי ⁠— לא מיתבא. בשתיה, בדידיה מיתבא דעתיה, בדחבריה ⁠— לא מיתבא דעתיה.

R' Zeira strongly objects to this halakha with regard to the measure for liability for drinking: What is different with regard to eating, in that all people have the same measure, the volume of a large date; and what is different with regard to drinking, where each and every person is liable according to his own measure, i.e., every individual’s measure depends on the size of his own mouth? Abaye said to him: The rabbis have an accepted tradition with regard to the volume of the large date, that eating this amount settles his mind, but less than this amount does not settle his mind. However, with regard to drinking, his mind is settled with the amount of his own cheekful, but his mind is not settled with the cheekful of his fellow who is smaller than him.

מתקיף לה רבי זירא: וכל העולם כולו בככותבת ועוג מלך הבשן בככותבת? אמר ליה אביי: קים להו לרבנן דבהכי מיתבא דעתיה, בציר מהכי לא מיתבא דעתיה, מיהו, כולי עלמא ⁠— טובא, ועוג מלך הבשן ⁠— פורתא.

R' Zeira strongly objects to this for a different reason: Is everyone of average size satisfied with eating the volume of a large date, and even Og, king of Bashan, is also satisfied with the volume of a large date? If not, there should also be relative measures for eating. Abaye said to him: The rabbis have an accepted tradition that this amount settles his mind, but less than this amount does not settle his mind. However, everyone of average size has his mind greatly settled, whereas Og, king of Bashan, has his mind only a little settled. But even so, this measure settles the mind of any person and relieves his affliction.