הלכה אויף דברים 13:1

Since the Beit Din has the capacity to declare laws and prohibit what is permissible, and its prohibitions last for generations, and similarly they have the capacity to permit that which is prohibited in the Torah for a specific situation. What does this mean that the Torah warns us (Deuteronomy 13:1) “Do not add to it and do not subtract from it”? That one should not add on to what is in the Torah and should not subtract from it, and make that thing set forever as something that is from the Torah, whether the Written Torah or the Oral Torah. How so? It is written in the Torah (Exodus 23:19) “Do not cook a kid in its mother’s milk.” From the interpretation they learn that this verse prohibits the cooking and eating of meat in milk, both the meat of a domesticated animal and the meat of a wild animal, but the meat of fowl is permissible in milk according to the Torah. If the Beit Din came and permitted wild animals in milk, this would be subtracting [from the Torah]. And if it prohibited the meat of fowl and said that it is included in [the wording of] “a kid,” and it is therefore prohibited according to the Torah, this would be adding on [to the Torah]. But if it [the Beit Din] said: “Meat of fowl is permitted from the Torah and we have prohibited it,” and we inform the people that this is a ruling that does not originate from that which is obligatory [in the Torah], they [the people] will say just as fowl is permissible [with milk] since it is not specified [in the Torah], so to [meat of a] wild animal is permissible [with milk] since it is not specified [in the Torah]. And then another will come and say that [meat of a] domesticated animal is permissible [with milk, according to the Torah], except for goat [meat]. And another will come and say that even meat of a goat is permissible with milk of a cow or a sheep, for the verse only says “its mother” who is of the same species [i.e. don’t cook a kid in its mother’s milk]. And another will come and say that even milk of a goat that is not its mother [i.e. the kid’s mother] is permissible [according to the Torah], for it only said “its mother.” Therefore, all meat in milk was prohibited, even meat of fowl. This is not adding to [the Torah] but is creating a fence around the Torah. And similarly anything like this.

but the commandment, which is the oral explanation of the Torah, he did not reduce to writing, but he charged the Elders and Joshua and the rest of all Israel concerning its observance, even as it is said: "All the word which I command you, that shall ye observe to do" (Deut. 13.1.); therefore, is this word of the commandment called, Oral Torah.

[When] one finished eating on the seventh day in the morning — he may not undo his sukkah. But he may bring down his vessels and evacuate them from the time of the afternoon prayer and onward. [If] he does not have a place to evacuate [his vessels] (like when the sukkah is in his house), he should reduce it four [handbreadths] by four. And if he needs to dine during the rest of the day, he needs to eat in the sukkah — since its commandment is for all seven [days].