Deuteronomy 16:5-6 -

Not in their own houses or places of abode might the Paschal lamb be slain and eaten, but only at the place, which the Lord should choose to place his Name there. On the first occasion, while the people were still in Egypt and had no sanctuary or specially holy place where Jehovah s Name was set, the Passover was eaten in their own houses; but when God should choose a place as his sanctuary, only there could the ordinance be observed.