Study Chagigah folio 18A with parallel Hebrew-English text, traditional commentary, and modern study tools. Free access to Babylonian Talmud online.
I would not know how many days of redress there are. The Talmud therefore teaches us, from the statement that R' Elazar said that R' Oshaya said, that there are 7 days of redress.
And Reish Lakish said, providing a different proof: From the very name of the day: “And the Festival of harvest” (Exodus 23:16), we can learn the following: On which Festival do you celebrate and harvest? You must say it is Shavuot. When exactly does this apply? If we say that it is on the Festival
R' Yoḥanan said to Reish Lakish: However, if that is so, you should likewise say with regard to “the Festival of gathering” (Exodus 23:16): On which Festival is there gathering? You must say it is the festival of Sukkot. When exactly? If we say it is on the Festival day itself, is labor permitted o
§ The Talmud comments: Since Reish Lakish does not dispute the accuracy of R' Yoḥanan’s statement, it may be inferred from their statements that both of them hold that the performance of labor during the intermediate Festival days is prohibited by the Torah.
The Talmud proceeds to ask: From where are these matters derived; what is the biblical source for this prohibition? As A baraita states: “You shall observe the festival of Passover 7 days” (Exodus 23:15). This teaches that the performance of labor is prohibited during the intermediate Festival days,