Jamieson, Fausset and Brown on Deuteronomy 16:5-6

5-6. Thou mayest not sacrifice the passover within any of thy gates--The passover was to be observed nowhere but in the court of the tabernacle or temple, as it was not a religious feast or sacramental occasion merely, but an actual sacrifice (Ex 12:27; 23:18; 34:25). The blood had to be sprinkled on the altar and in the place where the true Passover was afterwards to be sacrificed for us "at even, at the going down of the sun"--literally, "between the evenings."