Belzer Rebbe: Hillel’s source for eating the Korban Pesach in a sandwich (Korech) is not from the Parsha of Korban Pesach (Shemot 12), it’s from the Parsha of Pesach Sheni! Regarding Pesach Rishon it says: צלי אש ומצות. על מרורים יאכלוהו!
Some hold there is a misprint and the pasuk quoted should be the one from Parshat Bo. The Belzer Rebbe says that we say the pasuk from Pesach Sheni as a prayer that Moshiach should come by then.
Why does the Torah use a different phrasing describing Pesach Rishon vs. Pesach Sheni?
Shiur provided courtesy of Torah Anytime