The offering of the Passover Lamb was the most important religious act of the year. This lamb had to be a male, which was selected after minute examination, in order that it be free from any blemish, and it was to be a first year lamb. It was killed on the fourteenth of the month Abib (after the Babylonian captivity Nisan, about the equivalent of our April), and the blood was sprinkled with hyssop.
In Egypt the blood was sprinkled on the lintels and doorposts of the houses, but in Canaan it was sprinkled on the altar. The meat was roasted with fire, rather than boiled, and not a bone was broken, as was customary when it was boiled. It was eaten by the entire household in the spirit of haste, as if a journey was being started. Anything left of it was burned with fire, and not left over for the next day.
The Feast of the Passover was the most important of all the Jewish annual feasts, and formed the background for the Christian ordinance of the LORD's Supper.(cf. Exodus 12; Leviticus 23:5 ff.; Matthew 26:17-29).
[Manners And Customs of Bible Lands]