The Paschal lamb was slaughtered in three groups, meaning those bringing the offering were divided into three separate sets, as it is stated:”And the whole assembly of the congregation of Israel shall slaughter it in the afternoon” (Exodus 12:6). The verse is interpreted as referring to three groups: Assembly, congregation, and Israel. The procedure for sacrificing the offering was as follows: The first group of people sacrificing the offering entered, and when the Temple courtyard became filled with them they closed the doors of the Temple courtyard. They sounded uninterrupted, broken, and uninterrupted trumpet blasts, as was done while sacrificing any offering.
Then two rows of kohanim stood by with bezikhin in their hands, one row of gold and one row of silver. The kohen who stood near the place where the animals were slaughtered would catch the blood in the bazikh and it would be passed hand-to-hand to the kohen near the mizbe’ah who would sprinkle the blood on the altar. This same process was done with the second and third groups, as well. While this activity was taking place, Hallel was recited, as many times as was necessary, and although it was occasionally begun a third time, it was never completed more than twice.
The Bartenura and Tosafot Yom Tov describe the bazikh as a large pan with a handle, based on the Aramaic translation of the expression kaf ahat (see Bamidbar 7:14) as one bazikh. Others see it as a pot that is made in such a way that it does not have a flat bottom, which creates a situation in which the pot cannot be placed on the ground without falling over. This is important, as the blood collected in the bezikhin cannot be allowed to congeal.
As far as the Hallel is concerned, Rashi and Tosafot disagree about who recited the Hallel – was it the Levi’im or all of the people assembled there? A similar mahloket (disagreement) appears among the amora’im in the Jerusalem Talmud. It is also unclear what Hallel was being recited. Some say that it is what we call Hallel – the Hallel ha-Mitzri, which focuses on the exodus from Egypt (Tehillim 113-118). Others say that Hallel ha-Gadol (Tehillim 136) was also included. Some add Tehillim 135, as well, since it includes praise of God and it also refers to the Exodus.