Mark dates the meal precisely: “when they sacrificed the Passover lamb.” Passover (Pesach) was then a Temple feast: the lamb slain in the courts that afternoon, eaten that night with unleavened bread (matzah) and wine, in a room inside Jerusalem, in company: exactly the arrangements the disciples are sent to make. The hymn sung on the way out (14:26) would by long custom have been from the Hallel, Psalms 113–118, the Passover psalms: which means “the stone the builders rejected” (Psalm 118:22) was likely on His lips that night.