The Haggadah (הַגָּדָה, "telling"; plural: Haggadot) is a Jewish text that sets forth the order of the Passover Seder. According to Jewish practice, reading the Haggadah at the Seder table is a fulfillment of the mitzvah to each Jew to tell their children the story from the Book of Exodus about God bringing the Israelites out of slavery in Egypt, with a strong hand and an outstretched arm.
According to Jewish tradition, the Haggadah was compiled during the Mishnaic and Talmudic periods, although the exact date is unknown. It could not have been written earlier than the time of Judah bar Ilai (circa 170 CE), who is the latest tanna to be quoted therein. Abba Arika and Samuel of Nehardea (circa 230 CE) argued on the compilation of the Haggadah, and hence it had not been completed as of then. Based on a Talmudic statement, it was completed by the time of "Rav Nachman". There is a dispute, however, to which Rav Nachman the Talmud was referring: according to some commentators, this was Rav Nachman bar Yaakov (circa 280 CE), while others maintain this was Rav Nachman bar Yitzchak (360 CE).
However, the Malbim, along with a minority of commentators, believe that Abba Arika and Samuel were not arguing on its compilation, but rather on its interpretation, and hence it was completed before then. According to this explanation, the Haggadah was written during the lifetime of Judah ha-Nasi (who was a student of Judah bar Ilia and the teacher of Abba Arika and Samuel) the compiler of the Mishnah. The Malbim theorized that the Haggadah was written by Judah ha-Nasi himself.
One of the most ancient parts is the recital of the "Hallel," which, according to the Mishnah (Pesachim 5:7), was sung at the sacrifice in the Temple in Jerusalem, and of which, according to the school of Shammai, only the first chapter shall be recited. After the Psalms a blessing for the Redemption is to be said. This blessing, according to Rabbi Tarfon, runs as follows: "Praised art Thou, O Lord, King of the Universe, who hast redeemed us, and hast redeemed our fathers from Egypt.