Midrash su Levitico 23:41

1)1(Vayikra 23:41) ("And you shall celebrate it at a festival to the L–rd, seven days a year, a statute forever throughout your generations; on the seventh month you shall celebrate it.") "And you shall celebrate it as a festival to the L–rd seven days": Because it is written "And you shall celebrate it as a festival to the L–rd seven days," I might think that one must bring a festive offering (chagigah) all seven days; it is, therefore, written you shall celebrate it" — one day alone.

"And you shall celebrate it as a festival for the L rd": This tells me only of the first day of the festival as requiring a chagigah (offering). Whence do I derive (the same for) the last day? It is, therefore, written (Ibid. 13:6) "and on the seventh day, a festival (chag) to the L rd." This tells me only of the first and the last days as requiring a chagigah. Whence do I derive the same for the intermediate days of the festival (chol hamoed )? It follows inductively, viz.: Since the first and the last days are called mikra kodesh ("a calling of holiness") and chol hamoed is called mikra kodesh, then if you have learned about the former that they require a chagigah, then the latter, too, require a chagigah. And, furthermore, it follows a fortiori, viz.: If the first and last days, which are not preceded or followed by holy days, require a chagigah, how much more so (the days of) chol hamoed , which are preceded and followed by holy days! R. Yossi Haglili says: It is written (Devarim 16:15) "Seven days shall you celebrate ('tachog') to the L rd your G d," to include the seven days of Pesach as requiring a chagigah. __ But perhaps it speaks only of Succoth? (This is not so, for Leviticus 23:41) "And you shall celebrate it as a festival of the L rd" already speaks of Succoth. How, then, are we to understand "Seven days shall you celebrate"? To include the seven days of Pesach as requiring a chagigah.