What is the reason for reciting Song of Songs on Passover. What’s the connection?
It is customary to read Song of Songs on the first night of Passover at the end of the Seder. In the Diaspora where the Seder is repeated on the second night, the reading of this book is sometimes spread over the two nights, but it is more common for the whole book to be read on the first night.
In Ashkenazi communities, Song of Songs is read publicly in the synagogue on the Shabbat of Chol haMoed before the Torah reading. In some communities, it is actually read from a scroll, hand-written on parchment.
One reason for this is that Pharaoh is explicitly mentioned in this book. And in addition, Jewish sources relate the content of the book to the four different exiles and Israel’s redemption from each.
The Zohar states that Song of Songs embodies the entire Torah, the story of the exile in Egypt and the redemption of Israel from there, as well as from other oppressors, so that by reading it we are enhancing the mitzva of recounting the story of the Exodus.
Another reason for reading Song of Songs is that Passover is a special time of love between G‑d and Israel, who entered into a covenant and became betrothed to Him through the Exodus from Egypt. It is appropriate at this time that we recall the presence of that love at all times.