The Tanna Elokei [G-d like Tanna] R’ Shimon bar Yochai mentioned in the Sifri (Re’ah, 140) teaches: פסח וחג שאין עונת מלאכה עשה זה ז ’ וזה ח ’ עצרת שהיא עונת מלאכה אינה אלא יום אחד בלבד מלמד שחסך הכתוב על ישראל – “Pesach and Succos, which do not fall during the work season – He made one seven and the other eight. But Shavuos, which falls during the work season, is only one day. This teaches that the Torah spared Yisroel [the loss of work].”
The Bnei Yissoschar (Mamoray, Chodesh Sivan, Maamer 4) writes: “There are tens of thousands of reasons, for why Pesach and Succos are seven / eight days, whereas Shavuos which is Zeman Matan Torasainu [the festival all about the giving of the Torah] is only one.”
However, due to space and time constraints we will bring just one. The Madanay Asher suggests, that Shavuos is just one day, to teach us an important rule when it comes to Torah, a rule which we learn in Pirkei Avos. אל תאמר לכשאפנה אשנה שמא לא תפנה – “Don’t say when I have time I will learn, as perhaps you will never have time”. Many times, a person may think to himself, “today I don’t have any desire to learn, however, it’s not a problem, I will sit down and learn some other time”. Perhaps, for this reason, Shavuos which is the Yom Tov of Torah is specifically one day. By being only one day, we are taught that there is no opportunity for pushing Torah learning off, we must sit down and learn today, if we don’t learn today there will be no second chance to make up for it.
In the words of R’ Meir Shapiro: “Every day that passes by without Torah, is like a loss object, that will never be returned”.
