People who were unable to bring the paschal offering at its appointed time requested from Moses that they also be given an opportunity to perform the mitzva. In response, God provided a second Pesah, giving the opportunity to bring the offering a month later, on the fourteenth of Iyar. The Mishna enumerates the distinctions between the offering brought on the standard Pesah and the one brought on the second Pesah.

What is the difference between the paschal offering brought on the first Pesah and the one brought on the second Pesah? On the first Pesah, owning leavened bread is prohibited due to: “It shall not be seen,” and: “It shall not be found.” On the second Pesah it is permitted to have both leavened bread and matza with him in the house. The first Pesah requires the recitation of Hallel as the offering is eaten and the second Pesah does not require the recitation of Hallel as it is eaten. But both require the recitation of Hallel as the offerings are sacrificed, and for both, the offerings are eaten roasted with matza and bitter herbs, and their sacrifice overrides Shabbat. (Mishna Pesaĥim 9:3)