The Gemara establishes in Masekhet Sukka (26b) that although one who wishes to eat a light snack – as opposed to a meal – on Sukkot may do so outside the sukka, nevertheless, it is an acceptable chumra (measure of stringency) to avoid eating even light snacks and drinking outside the sukka. In the Gemara’s words, “leit bei mishum yuhara” – this does not constitute arrogance. Normally, following stringencies which are not strictly required bespeaks a degree of arrogance, but in this instance, ensuring to eat even small snacks in the sukka is deemed acceptable. Maharitz Chayot explains that this does not constitute arrogance because it is not outwardly evident that one eats in the sukka for the sake of stringency. People who see the individual eating a snack in the sukka do not know whether the individual eats only a snack or is eating this food as part of a larger meal – or, for that matter, is in any event in the sukka. Therefore, this is not regarded as a sign of arrogance.
The Talmud Yerushalmi (cited by the Magen Avraham, 640:16) tells that Rav Huna was once walking on Sukkot, and he felt thirsty. Although he had water with him, he did not drink until he arrived at a sukka, in accordance with this stringency. A number of writers demonstrated from this incident that it is acceptable to observe this stringency even if one experiences discomfort as a result. Although Rav Huna felt thirsty, he abstained from water for the sake of observing this measure of piety of ensuring to drink and eat only in the sukka throughout the holiday of Sukkot – showing that this stringency may be observed even if it causes discomfort.
By contrast, the work Olat Shemuel (98), cited in brief by the Chafetz Chaim in Bei’ur Halakha (639:7), maintained that one may not compromise his enjoyment of Yom Tov for the sake of following this stringency. The Olat Shemuel contends that although Rav Huna felt thirsty, he did not experience “tza’ar” (“distress”) such that waiting until he reached a sukka undermined his festivity. If his thirst had made him feel distressed, then he would not, according to the Ola Shemuel, have been permitted to deny himself water until he reached a sukka.
The Olat Shemuel explains on this basis why this stringency is acceptable, whereas the Rama (639:7), citing the Hagahot Maimoniyot, famously criticizes those who remain in the sukka when rain falls such that they are exempt from the mitzva. The Rama writes that these people do not earn reward for insisting on remaining in the sukka, and to the contrary, they are considered “hedyotot” (“fools”). The Olat Shemuel explains that in the case of rainfall, remaining in the sukka entails discomfort, and thus undermines one’s simchat Yom Tov – his enjoyment of the festival. By contrast, ensuring to eat and drink even small amounts in the sukka does not entail any discomfort. But if one indeed would experience discomfort by abstaining from food or water until he reaches the sukka, then, according to the Olat Shemuel, it would be improper to abide by this stringency, and he should eat or drink to avoid discomfort.