And in God´s Law already spoke of the sacrifice of his Lamb, only with bread without yeast. Exodus 34:
25- Thou shalt not offer the blood of my sacrifice with leaven; neither shall the sacrifice of the feast of the passover be left unto the morning. (For those who have supper with bread with yeast, these texts are very clear). Many make confusion with the supper, because it´s not well explained in the New Testament; to understand you have to compare with Judaic Easter (supper). (Exodus 12). Like in Egypt, the lamb was killed and eaten in the houses (for us, is where congregations gather – inner sanctum). The blood that freed them from death and slavery, now frees us from sin and eternal death.
Paul reprehends the Church in 1st Cor 11:
20- When ye come together therefore into one place, [this] is not to eat the Lord's supper.

(Because each one took his own supper, eat, drank and some even got drunk (because it was wine), the supper was a meal brought from home; this text shows us the resemblance between both suppers).
The people of God couldn´t eat Easter in their homes and cities, each family would take one or more lambs and go to Jerusalem around the temple, like the tabernacle in the desert (mobile temple = Christ, his body, the church).
Is in Deuteronomy 16.5 to 8 and confirms in Luke 2. 41, that the family of Jesus annually would go up by foot from Nazareth to Jerusalem (over 100 Km, to participate of Easter); about 15 days far from home in any weather, and the one that doesn´t participate (eat) would be eliminated form God´s people. This confirms in Numbers 9.13 Had to be purified to participate and eat the Easter. To confirm this you only have to read Ezra 6. 19 and also 2nd Chronics 30.