The Israelites killed the Passover lamb on the evening of the fourteenth day of the first month. Just as the Passover in Egypt marked the exodus from slavery, the celebration of this Passover in Canaan marked the attainment of the goal God had been leading the Israelites toward. This Passover also anticipated God's promised rest for his people in their new land.
This was apparently the first Passover feast Israel celebrated since camping at Mount Sinai (Numbers 9:1–5). For the younger Israelites, it was their first Passover feast ever. For the older ones, it was their first since childhood.
Celebrating Passover after such a long break increased both the joy and the serious nature of the occasion. This was especially true because it was before the campaign to capture the land God promised to give the Israelites.