Sukkah 47A

לברוכי. למאן דאמר שביעי לסוכה ⁠— ברוכי נמי מברכינן, למאן דאמר שמיני לזה ולזה ⁠— ברוכי לא מברכינן. אמר רב יוסף: נקוט דרבי יוחנן בידך, דרב הונא בר ביזנא וכל גדולי הדור איקלעו בסוכה בשמיני ספק שביעי. מיתב הוו יתבי, ברוכי לא בריכו.

with regard to whether or not to recite the blessing over residing in the sukka. According to the one who says that the status of the 8th day is like that of the 7th day with regard to the mitzva of sukka, we also recite the blessing: To reside in the sukka. However, according to the one who says that its status is like that of the 8th day both with regard to this and to that, we do not recite the blessing. Rav Yosef said: Take the statement of R' Yoḥanan that on the 8th day outside Eretz Yisrael one does not recite the blessing: To reside in the sukka, in your hand, i.e., adopt it as your practice. As Rav Huna bar Bizna and all the prominent scholars of the generation happened to visit a sukka on the 8th day, with regard to which there was uncertainty that it might be the 7th day, and they were sitting in the sukka, but they did not recite the blessing.

ודלמא סבירא להו כמאן דאמר: כיון שבירך יום טוב ראשון שוב אינו מברך? גמירי דמאפר אתו.

The Talmud suggests: And perhaps the reason they did not recite a blessing is that they hold in accordance with the opinion of the one who said: Once he recited the blessing on the first Festival day he does not recite it again on the subsequent days, and not because it was the 8th day. The Talmud answers: That is not the reason that they did not recite the blessing, as the rabbis learned through tradition that these rabbis were coming from the fields, where they had been herding their flocks, and that was the first time during the Festival that they sat in a sukka.